Neodymium (III) oxide (Nd Ox ) was dispersed in chitosan dissolution and deposited on a glassy carbon electrode (chitosan-Nd Ox /GCE). The surface properties of the chitosan-Nd Ox /GCE were evaluated with FeCN 6 ?3 solution using cyclic voltammetry and electrochemical impedance spectroscopy. The modified electrode was used in the determination of individual dopamine (DP) and ascorbic acid (AA) with square wave adsorptive voltammetry. Under optimal parameters (pH 4.0; accumulation time; t ACC 60s and accumulation potential; E ACC 0.10 V) for DP and (pH 3,0; t ACC 60s and; E ACC ?0.20 V) for AA, anodic peak currents were proportional to the concentration of DP and AA between 0.90 and 17.0 ?molL ?1 , with detection limit of 0.079 ?molL ?1 for DP and 0.12 ?molL ?1 for AA. The sensor was used in the determination of DP and AA in human urine samples and vitamin C tablets with consistent results. The new sensor is easy to develop. In addition, the sensitivity in particular for AA was improved compared with previous work.