An algorithm is presented for the construction of global reduced mechanisms, based on concepts from the Computational Singular Perturbation method. Input to the algorithm are (i) the detailed mechanism, (ii) a representative numerical solution of the problem under investigation, and (iii) the desired number of steps in the reduced mechanism. The algorithm numerically identifies the "steady-state" species and fast reactions and constructs the reduced mechanism. The stoichiometric coefficients are constant and are connected to the non "steady-state" species, while the related rates involve the slow elementary rates only. The proposed method is applied to a laminar premixed CH4/Air flame and a complex detailed chemical kinetics mechanism, consisting of 279 reactions and 49 species and accounting for both thermal and prompt NO, production. A seven-step mechanism is constructed which is shown to reproduce the species profiles and the laminar burning velocity very accurately over a wide range of values for the initial mixture composition and temperature. In addition, it is shown that the seven-step mechanism introduces much lower time scales than the detailed mechanism does. Since the proposed procedure for constructing reduced mechanisms is fully algorithmic and requires minor computations, it is very much suited for the simplification of large detailed mechanisms.