A new method for the measurement of two-dimensional heat flux profiles for GTAW processes is presented. The method is based on a least squares reconstruction algorithm for the inverse heat transfer problem for a steady-state temperature distribution in a specimen body. The temperature is measured with an experimental setup suited for the heat input of a welding process. The temperature distribution is then used to reconstruct the heat flux distribution on the specimen surface using a heat flux approach function. To calculate the temperature distribution ratio for the current approach heat flux profile, a numerical simulation model of the specimen is embedded in the reconstruction procedure. The residuum between the actual temperature distribution and the test function temperature is reduced using a least squares optimization step until convergence. The method is verified using a numerically calculated temperature distribution which is compared with a predefined heat flux profile. Moreover, the method is compared with a split-anode measurement for one-dimensional and two-dimensional reconstruction approaches. Measurements of a process with an inclined torch as well as a process with a magnetically deflected arc demonstrate the capability of the new method for the measurement of two-dimensionally resolved heat flux distributions of GTAW processes.