Co‐Ni‐P and Co‐P thin films have been electroless deposited on Al based Ni‐P plated substrates in the pH range 7.8–9.3. The effects of solution pH on nucleation, microstructure, and magnetic properties of these films were investigated by VSM, Auger, and electron microscopy techniques. The magnetic properties are dominated by the microstructure of these films. These two films, deposited at optimum pH, can be used for high density magnetic information storage media.