A man jailed for a series of sex attacks on Brisbane bikeways has won a reduction in his jail sentence.

Former landscaper Luke James Colless, 32, was jailed by a District Court judge last year for raping five women and sexually assaulting six others between 2006 and 2008.

The attacks happened in Brisbane inner-city suburbs including Paddington and Kangaroo Point.

It was after this last attack that a witness remembered the registration number of Colless's vehicle and reported it to police.

Colless was described as a sexual predator compelled to violently attack and rape women in public places.

In a decision handed down this morning, the Court of Appeal ruled Colless's 25-year jail term was excessive and cut it to 16 years.

The judgment said the court considered there were "substantial mitigating circumstances" and that Colless cooperated with the authorities from an early stage, including his confession, saving an even more substantial police investigation.

It said Colless's confession also removed any prospect of the complainants having to give evidence and be subjected to cross-examination, "thereby re-living their appalling experience".

The court said without his confessions, convictions might not have been obtained on some of the counts.

The court also noted Colless showed genuine remorse, did not have a prior criminal history and he had "promising prospects of rehabilitation".

Colless may serve less than 13 years before he is eligible for parole.

Political reaction

Premier Anna Bligh says the Attorney-General Cameron Dick is getting advice on a further appeal.

"The state does not support the reduction in this sentence - in fact we opposed this appeal in the strongest possible terms," she said.

"Obviously there are complex questions of law involved, but the Attorney-General is taking advice from the solicitor-general on whether there is any likelihood of a successful appeal to a higher court."

Opposition Leader John Paul Langbroek says the Court of Appeal decision does not reflect community standards.

"This was a matter that paralysed the suburbs for Brisbane for a number of months and it shows just how broken our justice system is when you have now almost 18 different rapes, attempted rapes and indecent assaults and the total length of time is 16 years," he said.