Abstract: A method of radiochemical separation of rubidium from complex system is described. The sample is decomposed with HF + HC1 +HNO3. Rubidium and cesium are precipitated with sodium tetraphenylborates.The precipitate is destroyed with HNO3 + HCIO4 and then changed into perchlorate. The perchlorate is dissolved in HCI and the resulting pulp is passed through anion and cation exchange columns for further purification. Rubidium is separated from cesium with zirconium phosphate. 83Rb and 84Rb are measured with a Ge(Li) detector.