Glassy carbon electrode modified with nickel oxide nanoparticles has been used to investigate the electrochemical oxidation of Glycine, l-Serine, and l-Alanine in an alkaloid solution. The electrochemical behavior of the modified electrode was characterized by cyclic voltammetry in detail. The electrocatalytic behavior is further exploited as a sensitive detection scheme for the above amino acids by hydrodynamic amperometry. Under optimized conditions, the calibration curves are linear in the concentration ranges of 1-200 mu M for Glycine, 1-400 mu M for l-Serine, and 30-200 mu M for l-Alanine, respectively. The respective detection limit (S/N = 3) and sensitivity are 0.9 mu M and 24.3 nA mu M-1 for Glycine, 0.85 mu M and 12.4 nA mu M-1 for l-Serine, and 29.67 mu M and 0.4 nA mu M-1 for l-Alanine. The prepared electrode exhibits a satisfactory stability and long life-time, while it is stored at ambient conditions.