Thin films of ferrites of various compositions have been prepared.Two methods have been developed, both involving a spraytechnique whereby hot suspensions of hydroxides are directedonto a heated substrate. The ferrite films are formed essentiallythrough a coprecipitation mechanism. X-ray diffraction has shownthat the films have a cubic spinel structure. Various compositionshave been attained; magnetite, nickel ferrous ferrite, a magnetite-zincferrite series, and other mixed ferrites. Coercive force measurementswere made from hysteresis loops obtained on a 1000-cycleloop tracer. The films are magnetically isotropic and have a highsquareness ratio. Film thicknesses have been varied from a fewhundred A to about 1 &mgr;. Relative film thicknesses were estimatedby using a spectrophotometric technique. For a fixed composition,coercive force decreases with increasing thickness. Magnetitefilms had coercive forces varying from 170 to 300 oe depending onthickness. A nickel ferrous ferrite series had coercive forces varyingfrom 225 oe for thick films to 400 oe for a very thin one. Coerciveforce measurements are related to composition variations in aseries of zinc ferrous ferrite films.