The electrochemical behavior of molybdenum with 1,10-phenanthroline was investigated in NaCl acidic medium. Adsorption phenomena were observed both by NPP and AC voltammetry. A linear current-concentration relationship was observed up to about 5 × 10-7 mol/L. The detection limit is 6 × 10-10 mol/L molybdenum after a 20 min accumulation time with a stirred solution. The reduction mechanism of the adsorbed complex was studied by square-wave voltammetry.