Abstract The concentration of 222Rn arising from a simple and practical radon generator, based upon solid 226Ra sources, has been measured. Sources were made by depositing a 226Ra standard solution onto several materials and drying. The encapsulated dried 226Ra source was connected to a second airtight capsule, and the collected 222Rn-laden air in the source capsule was transferred to the second capsule. After disconnecting the source, the concentration of 222Rn was measured by a Ge detector observing the 352-keV gamma rays from 214Pb. The activity ratios of 214Pb to the 226Ra with different source conditions were obtained. It was revealed that such dried 226Ra sources had good characteristics as the basis of a practical radon generator.