The UN special envoy on torture has said that his invitation to visit China indicates growing awareness in Beijing that the practice is still widely used.
Mr Nowak will spend nearly two weeks in China
Manfred Nowak told the BBC he had been promised the freedom to see prisoners and investigate claims of torture.
Mr Nowak will spend nearly two weeks in Beijing, Tibet and the troubled western province of Xinjiang.
Beijing outlawed torture in 1996, but human rights organisations report it is still used to extract confessions.
Mr Nowak's visit follows 10 years of repeated requests to be allowed into the country.
Speaking at the start of a two-week trip, he also said he was confident his recommendations would bring about change.
He said he was "grateful" China had allowed him the freedom to visit prisons un-announced and conduct private interviews with detainees.
"I see this as an opening up of government policy," he said.
"There is a growing awareness that torture is widely practised in common criminal proceedings," he said.
He cited recent cases where people were sentenced to death for murder - while their "victims" were later found to still be alive - as proof that torture is used to extract confessions.
Mr Nowak said he would make "realistic recommendations" to Beijing and he was confident they would be implemented.
"There is much going on in China in terms of legal reforms," he said, adding that he expected progress to take place in "small steps".