A tropical rainforest clearing experiment by biomass burning performed in a one hectare area of INPA's forest reserve located 60 km from Manaus, the capital of the Brazilian state of Amazonas, is described. The experiment is part of a major effort to quantify the amounts of carbon dioxide generated by this kind of clearing process. Following the procedure used by native people in the region, the trees were cut and the biomass left to dry on the ground for three months before burning. The fire burned through the whole one hectare area. The results include a carbon mass balance of the test site, air temperatures and heat transfer rates inside the ground. The carbon balance allowed the estimation of the carbon gasification efficiency for this kind of fire.