Abstract: A coalescing oil/water separator for removing free and dispersed oil from a wastewater stream with increased separation efficiency and producing a substantially oil-free effluent. The coalescing oil/water separator is self-contained in a tank shell and includes an improved oil coalescing medium for separating oil out of wastewater and a series of baffles and weirs to direct flow, skim the separated oil and control the liquid level in the separator. The improved oil coalescing medium is uniquely designed and sized to maximize the coalescing surface area in and the flow rate through a given volume of medium by including a plurality of molded, stackable perforated sheets or plates having an oleophilic surface and increased coalescing surface area for inducing impingement of oil droplets on the medium surface.