Following the energy ladder model, the role of biomass energy will diminish and even disappear as rural communities become more urbanized. However, the alternative fuel stacking model suggests that, as households become more urbanized, they diversify their energy sources while continue using firewood and charcoal. This study aimed to assess the extent to which biomass energy still plays an important role as a source of energy for household consumption across the urbanization spectrum of communities. Three villages in Khon Kaen province in Northeast Thailand representing the rural, suburban and urban communities were selected for study. Data were collected on energy uses at household level using a formal questionnaire survey along with field observation and field measurement. The results showed that total household energy consumption increased with urbanization. The absolute quantity of biomass energy used slightly increased when going from rural (5.52 GJ caput(-1) y(-1)) to suburban (6.06 GJ caput(-1) y(-1)) but greatly decreased for urban community (1.98 GJ caput(-1) y(-1)), while the relative share declined with greater urbanization, being 46.2, 37.4 and 10.2% for the rural, suburban and urban communities, respectively. Both firewood and charcoal were used primarily for cooking, with a small amount used for home industry. It was concluded that, although the share of biomass energy in household energy portfolios does decline relative to modern energy sources in the course of urbanization, as predicted by the energy ladder model, there is no sharp discontinuity in utilization of energy sources between communities at different stages of urbanization and biomass continue to be an important component of household energy portfolios in all communities, supporting the fuel stacking model. It appears likely that biomass will remain an important source of household energy in Thailand for an extended period. (C) 2011 Elsevier Ltd. All rights reserved.