Poly(o-aminophenol) (POAP) was formed by successive cyclic voltammetry in monomer solution in the presence of sodium dodecyl sulfate (SDS) on the surface of a carbon paste electrode (CPE). Ni(II) ions were incorporated into the electrode by immersion of the polymeric modified electrode having amine groups in 0.1 M Ni(II) ion solution. Electrochemical study of this modified electrode shows a good redox behavior of the Ni(III)/Ni(II) couple. The electrocatalytic oxidations of ceftazidim and cefazolin at the surface of the Ni/SDS-POAP/CPE were studied in a 0.1 M NaOH solution. Finally, using chronoamperometric method, the catalytic rate constants (k) for ceftazidim and cefazolin were calculated. Electrode was successfully applied for determination of ceftazidim and cefazolin in pharmaceutical preparations.