Sorption characteristics were determined of molecular sieve Zeolon 500 for106RuO4vapours. The sorption of106RuO4vapours decreased with increasing gas flow rate, it increased with increasing temperature. The sorption was found to be most efficient (penetration of 0.69%) at a flow rate of 0.25 l/min and a temperature of 300 °C. Sorption capacity up to 1% penetration was 76 mg Ru/g of the sorbent.106RuO4vapours were transformed into the gaseous phase during melting of a calcine prepared from a model waste solution following spent fuel reprocessing.