The magnetostrictive properties of Hiperco, a magnetic alloy of iron, cobalt, and chromium, were investigated to determine its suitability as a material for electromechanical transducers. The relations between the magnetic and magnetostrictive characteristics of a material and its performance as a transducer element are reviewed and criteria for its evaluation established. The properties of Hiperco, measured after a suitable heat treatment had been determined, are discussed in relation to these criteria and a comparison made with nickel and Permendur. For operation at magnetic remanence Hiperco is shown to be as good as Permendur for hydrophone applications, but inferior to nickel and Permendur when used as an underwater projector at high power levels. When polarized above remanence maximum value of 0.17 for the electromechanical coupling coefficient is realized and operation as a projector is improved. Performance data are given for a small underwater transducer constructed of Hiperco operating at remanence.