In the presence of glyoxalic acid and copper ion, pyridoxamine phosphate (PAM-P) was promptly converted into pyridoxal phosphate (PAL-P) non-enzymatically with high yield. In this reaction, formation of yellowish brown PAL-P-glyoxalic acid-Cu-chelate from PAL-P, glyoxalic acid, and copper ion was suggested by the ultraviolet absorption spectra and the analytical data. Pyridoxal phosphate-isonicotinic acid hydrazone (PAL-P-INAH) was obtained by the reaction of isonicotinic acid hydrazide after PAM-P was oxidized by colloidal MnO2. After removing the protecting group by 0.1 [image] HC1 and silver nitrite, PAL-P was purified by column chromatography using Dowex 50 W-X8 (H+ -form). This method, however, gave lower yield. Pyridoxamine, isopropylidene-pyridoxine, or deoxypyridoxine was allowed to react with P2O5 +85% H3PO4. Without separating the polyphosphate ester, the reaction mixture was hydrolyzed by 30% phosphoric acid which was produced by addition of water to the reaction mixture. Monophosphate ester thus formed was purified by baryta, charcoal, and Amberlite column chromatography and PAL-P, PIN-P, and deoxypyridoxine phosphate were obtained with high yields.