ABSTRACTPhysicochemical properties were compared on starch phosphates of cassava and corn, prepared by an extrusion process and by the conventional method, as well as their native starches. Results indicated that for preparing starch phosphates with similar degrees of substitution, the extrusion process required less reagent than the conventional method. The starch phosphates showed similar responses to heat treatment and pH changes. However, the starch phosphates made by extrusion had lower gelatinization temperatures, lower enthalpies and lower paste viscosities than those prepared by the conventional method. This result could be attributed to the high degree of damaged starch in the extruded products.