British Transport Police are seeking a man who sexually assaulted a woman who boarded a train at New Eltham station.
He left the train at the same station having travelled from Dartford.
The passenger had previously thrown a seat cover at another passenger as well as urinated on the floor.
The incidents occurred just after 2pm on Tuesday 4th April.
Anyone with information can contact British Transport Police by texting 61016 or calling 0800 40 50 40 quoting reference 326 of 4 April.