Microporous carbon catalysts with large surface areas (800–1100 m² g⁻¹) and high densities of SO₃H groups (ca. 1.1 mmol g⁻¹) were synthesized by sulfonation of zeolite-templated microporous carbon. The resulting SO₃H-bearing microporous carbon catalysts exhibited higher catalytic performance for the hydrolysis of cellobiose and the Beckmann rearrangement than conventional solid acid catalysts and non-porous amorphous carbon with SO₃H groups. The high catalytic activity of these reusable heterogeneous catalysts can be attributed to the high surface area and microporous structure, which enhance the efficient incorporation and diffusion of reactant molecules from solution to the SO₃H groups on the catalysts.