Diethyl (2- bromo -1- phenyl, vinyl) phosphonite and diethyl (1- chloro -1- phenyl, vinyl) phosphonate were allowed to react with mercuric acetate at different conditions inorder to eom» bine the organophosphorus and organomercuric compounds into one molecule and to study the effect of the vinyl group on the stability of P-C bond. Different mercurated products were ob- tained, some of them were due to cleavage of P-C bond with the formation of mercurated alip- hatic phosphonites and phosphonates and the others were formed through substitution and addi- tion reactions.