Abstract: New aminoalkylphosphonic acid esters of the formula ##STR1## wherein R is H or alkyl of up to 4 carbon atoms,R.sub.1 is H or CH.sub.3,R.sub.2 is H, CH.sub.3 or --C(R.sub.1)(NHR.sub.3)P(O)OR.sub.2, andR.sub.3 is H,--C(R.sub.1)(R.sub.2)P(O)(OR).sub.2 or --CH.sub.2 CH.sub.2 NHC(R.sub.1)(R.sub.2)P(O)(OR).sub.2,are prepared from (RO).sub.2 P(O)H, NH.sub.3 or ethylene diamine and formaldehyde, glyoxal, acetaldehyde or acetone. These new compounds can be reacted with methylol phosphorus compounds of the formulaP(CH.sub.2 OH).sub.4 Y or P(CH.sub.2 OH).sub.3where Y is an equivalent amount of the anion of at least one acid, and optionally additionally with urea. The reacting molar ratio of the hydroxymethyl phosphorus compound to the aminoalkylphosphonic acid ester is up to about 6:1 and preferably between about 0.5:1 and 3:1.