A novel experimental method has been developed and applied to measure the thermal conductivity of a thin (5.6 &mgr;m thick) boron‐doped diamond film produced by a hot filament CVD process. Thermal fields were created by Joule heating in a 3‐mm‐diam, free‐standing diamond diaphragm; infrared imaging thermography was used to quantify these fields. Parameter estimation was applied to determine the thermal conductivity of the film using more than 100 temperatures in each property determination. The experimental design chosen was selected on the basis of an analysis which maximized the sensitivity for the determination of thermal conductivity while minimizing the uncertainty in the estimation of this property. Parameters such as characteristic length, film resistivity, and thickness were chosen from the model to reduce convective effects, obtain the desired temperature rise, and minimize the uncertainty in the estimation of the thermal conductivity. Preliminary results for the thermal conductivity were obtained using the method of least squares to minimize the error between the measured temperatures recorded by the infrared temperature acquisition system and the calculated temperatures determined by the optimal radial heat flow model. A single doped film was energized at three power levels in five experiments. The thermal conductivity was determined to be 240±11 W/m K. The measured standard deviation of the mean matched the estimated uncertainty closely and the relative contributions to the experimental uncertainty have been quantified. ©1995 American Institute of Physics.