1. Experiments on the acylatlon of aminomethylphosphonic acid show that it proceeds with greater difficulty than the acylation of glycine. Acetamidomethyl-, (chloroacetamido)methyl-, and phthalimidamethyl-phosphonic acids have been prepared. 2. The methylation of aminomethylphosphonic acid has been effected by means of methyl iodide in a methanol mediums, and it has been shown that a quaternary iodide derived from the phosphonobetaine is formed. It is has been established that methylation proceeds at the expense of methanol, so hat much less than the stoichiometrlc amount of methyl iodide may be used.