In this study, electrochemical analysis of cefotaxime, one of the third-generation cephalosporins, the semisynthetic antibiotic group of the b-Lactam family, with an anodic pre-treated boron-doped diamond electrode (APTBDDE) were investigated in a wide pH range. The cyclic voltametric (CV) and square-wave voltametric (SWV) techniques were applied for the rapid, sensitive, cheap, simple, and precise detection of CEF. The compound yielded two well-defined oxidation steps (Ia=1.1; IIa=1.5 V) in acidic, neutral, and alkaline media by employing SWV. Experimental conditions, namely pH, modulation amplitude, step potential, frequency, interference, and effect of scan rate were optimized. By employing SWV, there was a linear dependence of the oxidation peak current at +1.1 V and CEF concentration in the range of 1.0-20.0 μg mL-1 (2.1×10-6 – 4.2×10-5 mol L-1), with a detection limit of 0.22 μg mL-1 (4.6×10-7 mol L-1) in 0.1 mol L-1 phosphate buffer solution (pH 2.5). The practical applicability of the proposed method was tested with the quantification of CEF in the drug formulation.