A 31-year-old man has been arrested on suspicion of indecent exposure at Sowerby Bridge rail station.
The incident happened at around 7pm on Thursday, November 17, when officers received reports of a man touching himself inappropriately.
The man was arrested and has now been released on police bail, to return on January 12.
Anyone with any information that may assist officers with their enquiries is asked to call 0800 40 50 40 or send a text to 61016 quoting reference 440 of 17/11/2016.
You can pass information anonymously to independent charity Crimestoppers on 0800 555 111.