In addition to size, density, composition and mineralogy (mineral type, texture, liberation, etc.), surface characteristics of sulphide minerals affects flotation behavior of sulphide ores considerably. The variations in surface characteristics of sulphide minerals can be related to the variations to the degree of surface oxidation which is known to influence the flotation performance. Surface oxidation affects dissolution behavior of sulphide minerals, activation/depression and adsorption of collectors, i.e. their flotation behavior. Therefore, a methodology, called "Oxidation Index" was developed to measure surface oxidation of sulphide minerals quantitatively and predict flotation behavior of different ore types. The methodology is based on derivation of an ore specific calibration curve and prediction of flotation performance of different ore types from the same deposit by using the calibration curve. The results of the test works performed using a complex Cu-Zn sulphide ore from Cayeli Bakir Isletmeleri A.S., Turkey are discussed in this paper. (C) 2012 Published by Elsevier Ltd.