A portable-scale thermoelectric power generator was designed, fabricated, and tested. The basis of the system is a mesoscale silicon reactor for the combustion of butane over an alumina-supported platinum catalyst. The system is integrated with commercial bismuth telluride thermoelectric modules to produce 5.8 W of electrical power with a chemical-to-electrical conversion efficiency of 2.5% (based on LHV). The energy and power densities of the demonstrated system are 321 W h kg-1 and 17 W kg-1, respectively. The pressure drop through the system is 130 Pa for the highest now rate used, resulting in a parasitic power requirement for air-pressurization of ~0.1 W. The demonstration represents an order-of-magnitude improvement in portable-scale electrical power from thermoelectrics and hydrocarbon fuels, and a notable increase in the conversion efficiency compared with previous studies.