The solvents tributylphosphate (TBP) and odourless kerosene (OK) are widely used to extract plutonium (IV) and uranium(V) in nuclearprocessing plants. Although these solvents are chosen because of their low affinity for fission products it is, nevertheless, of value to study ways of removing the small quantities of fission products, such as isotopes of Cs, Sr and Ru, which can be present in the solvents. This paper describes simple distribution coefficients (Kd) measurements made to test the ability of the aluminosilicate zeolites to remove 106Ru from TBP, OK, and their mixtures. The use of solvent extraction to affect separations of uranium and plutonium is the focal point of the Purex process designed for the recovery of U and Pu from irradiated natural uranium. The most commonly used solvents are tributylphosphate (TBP) and odourless kerosene (OK) chosen for many reasons, including their relative lack of affinity for common fission products. Despite this, some uptake of fission products such as the Cs, Sr and Ru isotopes occurs and it is of value to seek ways in which TBP and OK can be treated to remove these isotopes to aid waste management. Zeolites are hydrated aluminosilicates of high ion exchange capacity. They are readily available and find current use in the nuclear industry to scavenge fission products from aqueous wastes. A natural zeolite, clinoptilolite, is the key decontaminating agency in the BNF plc, Sellafield, SIXEP (Site Ion Exchange Plant) process,1 Zeolites are known to function as ion exchangers in non aqueous s' ~,~ts2,3 and so were chosen for this study which describes simple approaches using distribution coefficient (K a) measurements to investigate the uptake of I~ onto zeolites under circumstances appropriate to the nuclear industry. A second paper will describe a similar study on Cs and Sr radioisotopes.