An experimental burn was performed in a dambo grassland, in the Western Province of Zambia, during the SAFARI 2000 Third Intensive Field Campaign. The main goal of this study was to analyse the possibility of estimating combustion completeness based on fire‐induced spectral reflectance changes in surface. Inverse, nonlinear relationships were obtained between combustion completeness and pre‐fire to post‐fire spectral reflectance changes, in the green, red, and near‐infrared spectral domains (equivalent to Landsat 7 ETM+ channels 2, 3, and 4). The coefficient of determination (R ) varied from 0.50 for channel 4, to 0.57 for channel 3, and all the regressions were significant at the 95% confidence level. Thus, it may be feasible to treat combustion completeness as a variable whose values can be remotely estimated. However, its relationship with fire‐induced spectral reflectance changes is expected to exhibit some dependence on vegetation structure. The experimental burn was performed simultaneously with overpasses from the Terra satellite, and from the NASA ER‐2 research airplane carrying the 50‐channel MODIS Airborne Simulator (MAS) image spectrometer. Our results may be used in conjunction with imagery from these sensors, to support the development of operational approaches for combustion completeness estimation from remotely sensed data.