DL-1-aminobutylphosphonic acid was synthesized from the pentanoic acid which was prepared from the butyl alcohol, by the modified Curtius reaction. DL-2-amino-2-carboxyethylphosphonic acid was also synthesized from the pyruvic acid was also synthesized from the pyruvic acid. Four previously unreported N-acylated derivatives were prepared according to the modified Schotten-Baumann method. They are as follows; N-acetyl-DL-1-aminobutylphosphonic acid, N-benzoyl-DL-1-aminobutylphosphonic acid, N-benzoyl-DL-2-amino-2-carboxyethylphosphonic acid, N-p-chlorobenzoyl-DL-2-amino-2-carboxyethylphosphonic acid. The products were identified by the methods of elemental analysis, infrared spectra, ninhydrin test and neutralization equivalent.