The main reaction product of MnII catalysed periodate oxidation of 2,4-xylidine in acetone-water medium is 3,5- dimethyl-1,2-benzoquinone. The progress was followed by monitoring the increase in the absorbance of reaction intermediate. The reaction was found to be first order with respect to catalyst, substrate and oxidant each. The conditions were developed for kinetic-spectrophotometric determination of MnII in the range 0.54 – 345.22 ng/ml. Molar extinction coefficient and Sandell’s sensitivity for various calibration curves developed are respectively, 94149 to 148243 L mol-1 cm-1 and 0.82 to 1.3 ng cm-2. The characteristics of various calibration curves, percentage recovery, effect of interferrants and correlation coefficient etc have been evaluated. The method is better in terms of cost of analysis and ease of determination as well as involvement of easily available equipments and facilities