This invention is directed to an improved process for the preparation of N-(phosphonomethyl)glycine (i.e., "glyphosate"), a salt of N-(phosphonomethyl)glycine, or an ester of N-(phosphonomethyl)glycine. The process comprises combining an N-substituted N-(phosphonomethyl)glycine reactant with oxygen in the presence of a noble metal catalyst. The N-substituted N-(phosphonomethyl)glycine reactant has formula (V): ##STR00001## wherein R.sup.1 and R.sup.2 are independently selected from the group consisting of hydrogen, halogen, --PO.sub.3R.sup.12R.sup.13, --SO.sub.3R.sup.14, --NO.sub.2, hydrocarbyl, and substituted hydrocarbyl other than --CO.sub.2R.sup.15; and R.sup.7, R.sup.8, R.sup.9, R.sup.12, R.sup.13, R.sup.14 and R.sup.15 are independently selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl, and an agronomically acceptable cation.