A porphyry copper ore containing chalcopyrite as the principal copper bearing mineral, and pyrite as the only other sulphide mineral, was treated in batch flotation tests under well defined physical conditions., The size-by-size flotation response was benchmarked against established calibration curves to infer an operational contact angle of the sulphide minerals as a function of particle size. The inferred operational I contact angle values of the sulphide minerals were validated by independent measurements of contact angle on the concentrates and, in the case of chalcopyrite, by an indirect approach using Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS). Recovery, flotation rate, and inferred operational contact angle increased with collector addition across all size fractions, with the intermediate and coarse size fractions benefitting the most from increased collector addition. The directly measured and inferred operational contact angles were in reasonable agreement, with an R-2 value of 0.7 across all size fractions. There was good agreement between the advancing contact angle values determined using ToF-SIMS and those calculated from direct contact angle measurement on the 53-75 mu m size fraction for the case of chalcopyrite. A method for benchmarking flotation response has been developed, which may lead to better flotation process diagnostics and modelling. (C) 2011 Elsevier Ltd. All rights reserved.