The reactivity of reduction materials is critical in ferrosilicon and silicon production. The reactivity of different cokes has been measured with a method developed by Elkem ASA Research. The purpose of this work was to relate reactivity to petrographically determined parameters. It is easier and less costly to perform a petrographic analysis than to conduct the reactivity test. The relation between petrographic composition and reactivity has been established and a model for estimating the reactivity from the petrographic analysis was developed. The results of the current work show that petrographic analysis can be very useful in the selection of coals and cokes for the production of ferrosilicon and silicon. (C) 2000 Elsevier Science B.V. All rights reserved.