Pascoe has won her first gold medal at the Rio Paralympics today, her second medal at Games.

New Zealand swim star Sophie Pascoe has won her first gold medal of the Rio Paralympics.

A day after claiming silver in the women's 50m freestyle S10, Pascoe topped the heats in the 100m backstroke S10 on Sunday (NZ time) and backed that up with another impressive display in the final to regain the title she lost in London four years ago.

The 23-year-old finished in a time of 1:07.04, almost a full second ahead of Hungary's Binaka Pap with Britain's Alice Tai in third.

HAGEN HOPKINS/GETTY IMAGES New Zealand's Sophie Pascoe wipes away tears on the podium after winning a gold medal in the women's 100m backstroke S10 final at the Rio 2016 Paralympic Games.

"It was just about guts and digging deep," she said.

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BUDA MENDES/GETTY IMAGES New Zealand's Sophie Pascoe wipes away tears on the podium after winning a gold medal in the women's 100m backstroke S10 final at the Rio 2016 Paralympic Games.

It was Pascoe's seventh Paralympic gold - and 12th medal overall - adding to the six she won across the Beijing and London Games.

Having won gold in the event in 2008, Pascoe had to settle for silver in London as Canadian Summer Ashley Mortimer won in world record time.

Swimming in lane four on Sunday, it was clear from the outset that Pascoe was determined to go one better.

The Christchurch-based athlete found her rhythm early to take the lead by the first turn, built a handy advantage and despite a late surge by Pap, first place was never in doubt for the Kiwi.

"It was pretty tough in the pool tonight. I went out in the first 50m pretty much towards race plan and then the last 50m was hard, and they came back in the last 25," she said.

"Tonight was about coming out and getting the gold medal and that is exactly what I have done."

Pascoe cut an emotional figure on the dais, struggling to hold back the tears during the national anthem.

Her build-up to the Paralympics was struck by tragedy following the death of her friend and training partner, Hayley Edmond, to cancer earlier this month.

On Saturday, she dedicated her silver medal to Edmond.

Pascoe is back in the pool for heats of the 200m individual medley SM10 early on Monday morning NZT, with the final due at 10.07am.

Her victory came after New Zealand won four medals in an hour on Saturday (NZ time) and brings the medal tally to seven, comprising of three golds, two silver and two bronze.

That was the only medal of the day, though, as Mary Fisher couldn't replicate her scintillating form from Saturday as she finished fourth in the 400m freestyle S11 final.

Fisher, who set a new world record on the way to winning the 100m backstroke S11, was only ever in contention for bronze as eventual winner Liesette Bruinsma of the Netherlands and Italy's Cecilia Camellini raced clear.

However, she couldn't improve on her qualifying ranking, finishing in a time of 5:28.28 as China's Xie Qing rounded out the podium.

"I'm really happy with my performance because I could not have gone any faster today," Fisher said.

"Despite missing out on the final, Hamish McLean made a promising start to his first Paralympics.

The 16-year-old set a personal best time of 34.81 in the men's 50m freestyle S6 to finish 19th overall.

Meanwhile, Paralympic debutant Greg Reid has stormed into the final of the R3 - mixed 10m air rifle prone SH1.

Reid, a 54-year-old mass meteorologist from the Wairarapa, shot a total of 632.5 during the qualifying rounds to go from 30th to seventh overall.

He will be hoping to improve on fellow shooter Michael Johnson's effort after the four-time Paralympic finished fifth in the R4 mixed 10m air rifle standing SH2 event.

Anna Grimaldi, who won gold in the women's long jump T47 on Friday, qualified fifth fastest in the heats of the women's 100m, with a personal best of 12.88sec. The final is at 9.56am on Monday.

Across at the velodrome, Kate Horan finished sixth in the women's 500m time trial C4-5.

Horan was the ninth of 14 riders to take the track and set the pace with a time of 37.750.

However, that didn't last long as the remaining cyclists all posted faster times, Britain's Kadeena Cox claiming gold in 34.598.

Byron Raubenheimer failed to secure a spot in the finals of the 4km Pursuit C4, setting a time of 5:08.570 to finish in 10th place.

The full schedule for NZ athletes is here.