The pyrolysis kinetics of cellulosic uncoated printing and writing paper, which is one of the principal materials contributing to the municipal solid waste (MSW) of Taiwan, was investigated with a thermal gravimetric analysis (TGA) reaction system. The experiments were carried out in a nitrogen environment in the 450-850 K temperature range at various constant heating rates of 1, 2, and 5 K/min. The results indicated that there were two principal reactions in TGA curves as distinguished by the two significant and distinct mass changes over the experimental conditions. The pyrolysis of uncoated printing and writing paper can be adequately described by a two-reaction model. The corresponding activation energies, preexponential factors, and reaction orders were determined. The experimental results were satisfactorily fitted by the proposed chemical reaction model.