The assault is reported to have happened in Tesco Express on Bouverie Road West on the evening of Thursday 7 September 2023.
It is alleged that a man touched a woman inappropriately over her clothes.
On Monday 25 September, a 37-year-old man from the Folkestone area was arrested on suspicion of sexual assault.
He has been released on conditional bail while enquiries into the incident continue.
Anyone with information who has yet to speak to officers should contact Kent Police on 01843 222289, quoting reference 46/160947/23.
