The goal of the present study is to develop an optimized skeletal chemical kinetic mechanism for methane combustion, for conditions relevant to dual-fuel marine engines. To this end, a systematic approach is developed, consisting of the following steps: (a) assessment of three widely used detailed mechanisms, by comparing simulation results against three sets of indirect experimental data pertinent to methane combustion, (b) sensitivity analysis, with identification of important reactions (species), (c) selection of one detailed mechanism and production of a skeletal mechanism by means of the simulation error minimization connectivity method, (d) uncertainty analysis of the rate constants of important reactions, and (e) optimization of the skeletal mechanism for the rate constant parameters of the important reactions. The resulting optimized skeletal mechanism, consisting of 28 species and 119 elementary reactions, accurately reproduces experimental data in a wide range of conditions and is an important development for computational fluid dynamics studies in dual-fuel marine engines.