The ternary CoNiP soft magnetic films were deposited on silicon substrates by the autocatalytic electroless process. The deposition of these magnetic thin films was carried out by using different concentrations of cobalt (Co2+), nickel (Ni2+) and hypophosphite (H2PO2-) ions in the bath, and by maintaining the bath at different pH levels. The composition and the magnetic characteristics of the deposited films were studied. The effects of varying the concentration of both metal ions and nonmetal ion (reducing agent) on the magnetic properties of the films were explored by increasing the concentration of precursor salts of Co2+ ions from 0.002 to 0.008 M, Ni2+ ions from 0.004 to 0.02 M, and H2PO2- ions from 0.02 to 0.25 M. The pH of the bath was varied in the range 7.0-9.0 in steps of 0.5. The magnetic moment and coercivity of the CoNiP films decreased when the concentrations of the metal ion was increased. However, when the pH was increased, the magnetic moment increased with a corresponding reduction in the coercivity values. Maintaining the bath pH within a narrow range of 8.5 to 9.0 was found to be critical for the formation of high quality soft-magnetic films which exhibit large magnetic moments and low coercivity. (C) 2003 The Electrochemical Society.