The man remains in a critical condition in St Vincent’s Hospital.
He is described as being 1.72m (5’8″) and of thin build with short grey hair. He was wearing a wine coloured jacket, a black t-shirt and dark tracksuit bottoms.
Gardaí have identified him but are trying to establish how he sustained his injuries.
They have appealed to anyone who may have seen the man between 11.35pm on Monday and 5.55am on Tuesday to contact Bray Garda Station on 01-6665300.