Abstract: Chemically phosphorylated soy protein products with much improved functional properties and useful in food industries can be prepared through series of steps: (1) isoelectric washing the defatted soy flour, (2) extracting the proteins present in defatted soy flour in an aqueous medium of the extreme pH value below or above the isoelectric point of soy proteins, (3) alkalifying the extract of soy proteins to pH 11-12 by the addition of concentrated alkali in a short time, (4) modifying the extracted soy proteins under alkaline condition and at ambient temperature by the addition of powdered sodium trimetaphosphate as a phosphorylating agent and (5) recovering the phosphorylated soy protein products by isoelectric washing and final spray-drying as a powder.