The water-soluble organophosphorus compound, namely, hexahydroxymethylamidocyclotriphosphatriazatriene (HHMAPT) was synthesized by reacting phosphonitrile chloride with liquid ammonia followed by reaction with formaldehyde. It is rich in phosphorus and nitrogen and as a polyfunctional compound it can undergo several reactions with itself forming an in situ polymer or with cotton cellulose similar to conventional N-methylol 5nishing agents. It was successfully used as a 6ame retarding agent in the absence and presence of etheri5ed methylolated melamine (EMM). Investigations into the di4erent factors that a4ect these reactions and the e4ect of these on the properties of the 5nished fabrics give rise to the following points; (1) P%, N% and crease recovery increase by increasing the curing time and temperature; (2) the most e4ective catalyst is NH 4 Cl; P% and N% increase by increasing the concentration of NH 4 Cl from 5 to 12.5 g/l (3) an increase in EMM and HHMAPT concentrations is accompanied by enhancement in P%, N% and crease recovery; (4) the fabric samples exhibit durable 6ame retardancy at temperatures higher than 1203C in the absence of EMM while in the presence of EMM, all samples exhibit durable 6ame retardancy properties, regardless of the temperature of curing; (5) the durable 6ame retardancy is achieved at concentrations higher than 60 g/l HHMAPT and 7.5 g/NH 4 Cl. All samples exhibit loss in tensile properties but within an acceptable range (20%), crease recovery is improved in all samples.