Former Australian soldier Curtis McGrath has won a gold medal in his para-canoe KL2 event on day eight at the Rio Paralympics.

Overall, the Australian team won four gold medals across three sports, making a total of 14 golds for the Games and fifth place on the medal tally.

McGrath set a new personal best time of 42.190 seconds, winning the 200m event from Austrian competitor Markus Swoboda in 43.726.

McGrath got off to a strong start, although Swoboda was in front in the early stages. But he pulled ahead in the second half of the race to win comfortably.

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He lost both legs and injured his wrist in the blast, but as he was being airlifted out he vowed to his unit to represent Australia at the Paralympics.

After months of intensive rehabilitation, McGrath began an intensive training program to make the Paralympic squad for Rio, that culminated in a gold medal performance at Lagoa.

"It's pretty special ... for me to claim the top spot I'm pretty stoked," McGrath told Channel Seven.

"I'd run over the race in my head first - I did that and it actually happened (in the race).

"It's a bit of sense of relief. I was very nervous, I think everyone was.

"I guess there's times when it's quiet you have a bit of reflection time and think what could have happened, and just be thankful my life was saved by the guys on the hill.

"This gold is for me and for all the people who supported me."

On finals day for para-canoe - which is making its debut at the Rio Paralympics - Australia won three medals in total.

Amanda Reynolds took silver in the women's KL3 final, beaten by 0.03 of a second by British gold medallist Anne Dickins.

In the women's KL2 final, Susan Seipel finished in 56.796 seconds to win a bronze medal behind another British winner Emma Wiggs (53.288).

Thomas Kane claims gold in 100m breaststroke

Tiffany Thomas Kane broke through for her first gold medal in Rio in the 100m breaststroke SB6 final. ( Getty Images: Friedemann Vogel )

In the pool, Australia won a second gold medal of the day with Tiffany Thomas Kane claiming the 100m breaststroke SB6 event.

World record-holder Thomas Kane had broken the Paralympic record in the heats on day eight, registering the fastest time of the morning by nearly three seconds.

She was challenged in the final by American swimmer Sophie Herzog, who led the field out at the 50m mark, but Thomas Kane came home fast and took the lead with 20m left to claim gold in one minute 35.39 seconds.

"I don't know - I just wanted to go for it," Thomas Kane told Channel Seven.

"I didn't care if I didn't get a world record ... I'm so happy that I went out there and finally got a gold medal."

The 15-year-old year nine student from Ravenswood school in Sydney had already won three bronze medals in Rio before breaking through for a Paralympic title.

"It's very sweet given I wanted to get a different colour and wanted to hear a different jingle (sound in the medal)."

Tanya Huebner came sixth in the same final in 1:42.66 while Kate Wilson finished eighth in 1:49.21.

Monique Murphy won a silver medal in the final of her pet event, the 400m freestyle S10.

Murphy finished in 4:35.09 behind Canadian gold medallist Aurelie Rivard, who broke the world and Paralympic records in 4:29.96.

An emotional Murphy was still coming to terms with her result after the race, two years after losing her leg and being in a coma due to a fall from a fifth-floor balcony.

"It's really hard, it (the race) really hurt," she told Channel Seven.

"I just came her to do a PB, I was a bit off that - but it's really tough, thinking where I was two years ago. I'm just proud to be here.

Murphy thanked her family and friends for helping her recovery, and the Australian Dolphins swim team.

"(They taught me) it's not a disability, it's just another challenge."

In the men's 400m freestyle S10 final, Australia's Rowan Crothers came sixth in four minutes 10.83 seconds, while Guy Harrison-Murray was eighth in 4:11.18.

Australia finished off the day with another gold in the women's 4x100m relay 34 points final.

Ellie Cole led off with a strong swim, then Lakeisha Patterson and Maddison Elliott extended the lead to give Ashleigh McConnell a seven-second break on the field going into the anchor leg.

American anchor Michele Konkoly came home with a wet sail to take time off McConnell, but the Australians were always going to win and McConnell touched the wall in a new world record of 4:16.65, taking 3.64 seconds off their own world mark from London.

"That was one of our records from London, but the last few days I've been absolutely obsessed with the relays," Ellie Cole told Channel Seven.

"We can all walk away with a gold medal now!"

Elliott, who was also part of the winning team in London, said: "To be back-to-back Paralympic gold medallists, with another world record, especially with these girls, is just amazing."

Reardon takes out 100m T42 final

Scott Reardon took out Australia's third gold medal of the day, winning the 100m T42 final in a dramatic race.

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Reardon got off the blocks well and looked comfortably in front entering the closing stages of the race, but a blistering finish from Britain's Richard Whitehead nearly grabbed the win.

The Australian held on, equalling the Paralympic record in 12.26 seconds, ahead of Denmark's Daniel Wagner and Whitehead, who dead-heated for silver in 12.32.

"That's seven years of hard work under a really good coach," Reardon told Channel Seven, praising mentor Iryna Dvoskina.

"To do that for her and everyone who's come before including Heath (Francis) ... I'm just glad to do this for Iryna.

"I'm 165 cms tall I shouldn't be mixing it with these guys.

"The gold was the goal ... it was a bit messy but we got it up in the end."

There was mixed news for Australia's relay teams. The women's 4x400m T53/54 wheelchair racers team, of Angie Ballard, Madison di Rozario, Jemima Moore and Christie Dawes finished third in the final behind the dominant Chinese team - who broke the world record by eight seconds - only to be disqualified after the event.

However in the women's 4x100m T35-38 relay, the Australian team of Ella Pardy, Isis Holt, Jodi Elkington-Jones and Erin Cleaver finished third behind China, who also broke the world record in 50.81 seconds.

Di Rosario had earlier missed out on the medals by just 0.12 seconds in the final of the women's 5,000m T53/54 final. Di Rosario finished fourth behind American trio Tatyana McFadden, Chelsea McClammer and Amanda McCrory.

Australia's Jayden Sawyer finished fifth in the men's F38 javelin final, with a throw of 45.63m. Sawyer finished behind South African gold medallist Reinhardt Hamman (50.96m).

On the track, Jarryd Clifford finished seventh in the men's 5,000m T13. Clifford raced a personal best of 15 minutes 06.64 seconds, behind winner Henry Kirwa of Kenya.

Australian sailors in pole position

In the Sonar, three-person boat category, Australia's Colin Harrison, Jonathan Harris and Russell Boaden won race seven before a third-place finish in race eight on the waters at Marina de Gloria.

The crew leads with 16 points with three races left, ahead of their nearest competitor the United States on 27 points.

Defending champions in the Skud-18 (two-person keelboat) category, Australia's Liesl Tesch and Daniel Fitzgibbon, consolidated their overall lead with victories in race seven and eight.

Tesch and Fitzgibbon are on eight points after eight races, ahead of the Canadian and British crews who are both on 23 points.

In the 2.4mR (single-person keelboat) category, Australia's Matthew Bugg had a win and second-place finish in the day's two races.

The results pushed Bugg into first place on 16 points with three races left, a point ahead of British sailor Helena Lucas.

There are two days of competition left before the medals are decided.

In wheelchair rugby, Australia had an easy win, with the Steelers beating hosts Brazil 72-45. Star player Ryley Batt led the way with 34 points.