The invention relates to a process for alkylating a hydrocarbon feed which comprises contacting the hydrocarbon feed to be alkylated with an alkylation agent in the presence of a catalyst comprising a solid acid, a hydrogenation metal, and 1.5-6 wt % of water, measured as the loss on ignition at 600.degree. C. The presence of 1.5-6 wt % of water results in a higher activity and a higher alkylate quality compared with a comparable but drier catalyst.