A kind of energy grass (giant reedgrass) with high calorific value, high production, low land requirement and low sulfur dioxide emission is introduced into lignite pyrolysis process in this paper. Individual pyrolysis and co-pyrolysis characteristics of energy grass and lignite are investigated by the thermogravimetric analyzer together with mass spectrometer. The individual decomposition indicates that energy grass possesses higher thermochemical reactivity and shorter devolatilization time than lignite. The maximum decomposition rate increases with increasing the heating rate for both energy grass and lignite. The mass spectrometric analysis reveals that the emission of sulfur dioxide from energy grass is much lower than that from lignite. The co-pyrolysis of energy grass and lignite blend is characterized by two-stage thermal degradation processes, which is dominant by energy grass content in the first stage but lignite in the second stage. No obvious interaction between energy grass and lignite is observed during the co-pyrolysis process under the operational conditions investigated in this study. Moreover, the distributed activation energy model is applied to determine the activation energy for the pyrolysis of energy grass, lignite and their blends. (C) 2015 Elsevier Ltd. All rights reserved.