Included are halogenated phosphate-phosphites and their acid halides and acids. The halogenated phosphate-phosphites can be prepared by a process comprising serially contacting(A) a phosphorus trihalide with a triol;(B) a halogenating agent; and(C) an oxirane or an alcohol,under conditions sufficient to prepare the halogenated phosphate-phosphite. Steps (A) and (B) can prepare their acid halides. Use of water in step (C) can prepare their acids. For example, 3-((bis(2-chloroethoxy)phosphino)oxy)(2-bromomethyl-2-methylpropyl, 2-bromoethyl, 2-chloroethyl)-phosphorate can be prepared from 2-methyl-2-(hydroxymethyl)-1,3-propanediol; phosphorus trichloride; bromine; and ethylene oxide.Also included is use of the compounds as a hydraulic fluid or flame retardant. For example, polyurethanes can be rendered less flammable with the halogenated phosphate-phosphite flame retardant.