The 33-year-old woman was approached by the man as she was getting off of a train in Huddersfield.
They walked towards McDonalds before leaving the town centre.
As they were walking, the man grabbed the woman and sexually assaulted her in a doorway
He then picked up the woman’s bag and phone and walked off.
Police have today released a CCTV image of a man they want to identify in connection with the assault - which took place on Sunday, June 23.
The suspect was described as white male, with olive skin, late 30s, around 5ft 7” and slim build.
He was wearing black slim fit jeans, dark coloured top, black woolly hat and black Nike trainers.
Anyone who recognises to man in the image, witnessed the incident or has any further information is asked to contact the police via 101 quoting crime reference number 13190320511.