Abstract: A prolonged action cephalosporin was prepared by the reaction of cefotaxime sodium (CTX) with N, N-dibenzylethylene diamine acetate. It is reasonable to consider the resultant as benzathine cefotaxime (BCTX) by means of elemental analysis, DSC, UV spectra, IR spectra, NMR spectra and mass spectra. In contrast to CTX, BCTX appeared to be almost insoluble in water and its intrinsic dissolution rate was 0.183μg/ml·min. The stability revealed that the degradation of BCTX suspension in water followed zero-order kinetics and the rate of degradation at room temperature was found to be 1.67×10^-7mg/ml·s.An in vivo test by using 12 rabbits given BCTX sttspension and CTX solution intramuscularly was conducted. The results showed that the former was longer in maintaining serum drug level than the latter.