The 37-year-old was walking near Dalmuir railway station, near Clydebank in West Dunbartonshire, in the early hours of Saturday when the "terrifying" attack happened.
The victim was approached by the man who began talking to her as they walked in the same direction.
As they made their way towards Glendevon Place, the man forced the woman onto waste ground where he raped her.
The man then ran off towards Dalmuir.
The attack took place between 1.30 and 2.30am.
Detectives are searching through CCTV footage in bid to find clues.
And they are appealing for anyone who may have seen or heard the attack to come forward.
The man is described as white, around 5ft 4in, of medium build, with fair hair and he was wearing dark coloured denim.
Detective Sergeant Gerry Shovlin, of Clydebank CID, said: "The man started chatting to her and said he was going in the same direction so she was okay for him to walk with her.
"However, this turned into a terrifying attack and we are determined to find the man responsible."
Anyone with information is asked to call Clydebank Police Office on 0141 532 3300 or Crimestoppers on 0800 555 111.
Meanwhile, police in the West End of Glasgow are continuing to hunt a serial sex attacker who followed and assaulted three women in the space of two weeks.
A 23-year-old woman was attacked on January 24 at 4.20pm in a common close in Great Western Road.
In the second incident, on January 31, a 19-year-old woman was assaulted in a close in Arlington Street shortly before 6.30pm.
And in another attack, on February 3, a 20-year-old woman was attacked in a close in Kersland Street at around 5pm.