Some new phosphorus(V) hydrazides 1a-12a were synthesized and characterized by (1)H, (13)C, (31)P NMR, IR spectroscopy and elemental analysis. Moreover, the interaction of Cu(M)(2)·nH(2)O with 1a, 3a and 7a gave 4,4'-bis(morpholine)diazene (1b). In fact, in these reactions, copper(II) ions acted as oxidizing agent. The results supported the proposed mechanism. The structures of compounds 1a, 1b and 1c were further determined by X-ray crystallography. Compounds 1a-12a were screened for their antibacterial activities. Also, the acetyl- and butyrylcholinesterase inhibitory activity of 1a, 3a, 7a, 11a and 12a was measured using Ellman's method. It is interesting that these compounds were more potent inhibitors of BChE than of AChE. Also, using Lineweaver-Burk plots, it was indicated these compounds are mixed inhibitors.