Display omitted •Activated carbon prepared from a lignin/urea/K2CO3 mixture provides a high specific surface area and a large pore volume.•Part of the urea nitrogen present in the mixture is retained as heterocyclic nitrogen in the solid phase after activation/carbonization.•Pore development is thought to proceed through interactions between K-species and C–N forms. The present work focuses on the role of nitrogen in the development of pores in activated carbon produced from lignin by K2CO3 activation, employing a fixed bed reactor under a high-purity He stream at temperatures of 500–900°C. The specific surface area and pore volume obtained by activation of lignin alone are 230m2/g and 0.13cm3/g at 800°C, and 540m2/g and 0.31cm3/g at 900°C, respectively. Activation of a mixture of lignin and urea provides a significant increase in the surface area and volume, respectively reaching 3300–3400m2/g and 2.0–2.3cm3/g after holding at 800–900°C for 1h. Heating a lignin/urea/K2CO3 mixture leads to a significant decrease in the yield of released N-containing gases compared to the results for urea alone and a lignin/urea mixture, and most of the nitrogen in the urea is retained in the solid phase. X-ray photoelectron spectroscopy and X-ray diffraction analyses clearly show that part of the remaining nitrogen is present in heterocyclic structures (for example, pyridinic and pyrrolic nitrogen), and the rest is contained as KOCN at ≤600°C and as KCN at ≥700°C, such that the latter two compounds can be almost completely removed by water washing. The fate of nitrogen during heating of lignin/urea/K2CO3 and role of nitrogen in pore development in activated carbon are discussed on the basis of the results mentioned above.