Composite polyamide membranes were prepared by the in-situ interfacial polymerization over polysulfone and polyethersulfone support membranes using three different amines namely, polyethylene imine, 1.4- phenylene diamine and piperazine with difunctional and trifunctional aromatic acid chlorides. Separation performances of the membranes were studied with respect to sodium chloride and magnesium sulfate solutes. The effect of pH of feed on composite membrane performances is also studied. Polyethylene imine and 1,4- phenylene diamine give reverse osmosis (RO) type membranes but piperazine gives nanofiltration (NF) type membrane over both polysulfone and polyethersulfone supports. Composite membranes formed over polyethersulfone supports show better salt rejecting properties with relatively less product permeation rate than that formed over polysulfone supports. Polyethylene imine based composite membranes show better performance at the acidic feed whereas 1,4- phenylene diamine and anhydrous piperazine based membranes showed better performance at the alkaline feed. © MD Publications Pvt. Ltd.