In the near future, research on new materials for radon barriers can be expected to rise in order to meet a greater demand of radon mitigation solutions because of the increasingly lower radon levels that the EU legislation aims to. Such research would need a method for the determination of the radon diffusion coefficient and this paper presents an inexpensive method for that purpose, using affordable radon detectors and a simple experimental setup that does not require any tubing or any pumping. Besides the use of two Electronic Integration Devices as radon detectors, the experimental setup used in our method consists only in a two-chamber container made of steel and a small-sized radon source, which was produced in our lab using a 226Ra solution. The radon diffusion coefficient is determined by measuring radon levels in both chambers of the container, which are separated by a membrane made of the material whose radon diffusion coefficient is to be determined. Radon diffuses from a source chamber to a receiver chamber trough the membrane, being the amount of radon that has passed through and the rate at which it has done so the key parameters in the calculation of the radon diffusion coefficient. Our method can handily measure materials with a radon diffusion coefficient above or equal to 10-11 m2 s-1 or, provided that the sample is thin enough, verify that the coefficient is lower than 10-12 m2 s-1. Its precision is good enough to provide radon coefficient diffusion values with a good repeatability as the RSD is as low as a 35% for materials in which the coefficient is in the order of 10-11 m2 s-1. This means that our method is valid for screening materials for radon barriers and checking their compliance with technical specifications. Display omitted •New and inexpensive method for the determination of the radon diffusion coefficient, using a simple experimental setup.•Two Electronic Integration Devices are used as radon detectors inside an airtight container, with a small-sized radon source.•This method can measure materials with low radon diffusion coefficients, allowing the screening materials for radon barriers.