Two Comancheros bikie gang associates have been charged as a result of an assault at a Northbridge nightclub in May.

Police allege the assault happened just after midnight on May 28 in the upstairs bar of the Library.

One of the men allegedly punched the victim in the jaw, knocking him unconscious.

Police say the victim fell to the floor and the other man kicked him in the head as he lay there.

The unconscious man, who is a 25-year-old from Victoria Park, ended up with concussion, a swollen jaw and a cut elbow.

The gang crime squad charged a 22-year-old Kiara man and a 20-year-old Dianella man with assault occasioning bodily harm.

Both men will appear in Perth Magistrates Court on August 23.