Fire behavior models are essential components of fire management decision support systems (DSS). Such models allow the estimation of fire behavior characteristics; information that is needed for prescribed fire planning, tactical decision support during ongoing wildfires and the evaluation of alternative treatments for fire hazard reduction at the stand and landscape level. The use of physical based fire behavior models in DSS has been hindered by the difficulty in quantifying fundamental combustion, heat transfer and fluid flow processes in outdoor fires. As such, these models are built on untested theories or based on parameters determined in small-scale laboratory fires. Within the present study we measured the distribution of flame radiant heat fluxes in shrubland experimental fires. The experimental fires were conducted over a wide range of fire environment conditions. Flame radiant heat fluxes were measured with narrow angle radiometers at three different heights in the flames. Measured peak heat fluxes varied between 165.6 and 23.6 kW-m-2. Parameters such as flame emissivity, radiometric temperature and reaction time were derived from the data collected. The data collected in these experimental fires will be used in the evaluation of critical assumptions in physical fire behavior models.