Biofuels, such as biohydrogen, biomethanol, bioethanol and biodiesel may be the future of energy for transportation. The methanol can be used directly for powering Otto engines or fuel cells; it is commonly used in biodiesel production for its reactivity. Biohydrogen is a replacement for fossil and biorenewable liquid fuels. Based on a mechanism composed by 20 reversible elementary reactions among 8 reactive species, we propose a reduction process to obtain the mechanism of hydrogen, and from 136 reversible elementary reactions among 30 reactive species, we obtain a reduced mechanism for methanol, considering velocity and concentration of each elementary reaction. The aim of this work is the development of a numerical algorithm which eliminates the fastest reactions that destroy the steady-state species since the slowest reactions are rate-determining. The reduction strategy may be summarized in 7 steps: 1. Estimate the order of magnitude of the reaction partners; 2. Apply steady-state assumptions to those species whose concentration remains small; 3. Define the main chain; 4. Identify global reactions and their principal rates; 5. Introduce partial equilibrium assumptions; 6. Justify the assumptions by asymptotic analysis; 7. Identify the limitations of the strategy. Results show that the main advantage of the reduced reaction mechanism is the reduced stiffness of the system of equations.