A procedure to measure the diffusion coefficient of water in brick as a function of the water concentration has been proposed, based on a method of measuring the mass of a drying brick at both outer ends. In this method, the brick is subjected to one-dimensional drying. The procedure was tested using a simulation with realistic parameter values and experimental inaccuracies. An experiment consisted of 120 s of drying and measuring the masses every 10 s with an accuracy of 10-6 kg. The sample was first dried to a lower water content and the drying was stopped for some time to allow the concentration profile to approximate a known equilibrium concentration profile, after which another measurement was performed at that lower water content. Minimizing the differences between the masses, as measured and as it follows from the model, gave the value of the diffusion coefficient. The method failed for low water concentrations.