A hydrazine oxalate [(N2H5)2C2O4] solution was used as an alternative wash method for cleaning 30% tributyl phosphate—70% normal paraffin hydrocarbon solvent. Experimental evidence shows the (N2H5)2C2O4 wash solutions to be as effective as hydrazine carbonate [(N2H5)2CO3] or sodium carbonate (Na2CO3) in cleanup of test solvents. Major advantages of the alternative method are: (a) (N2H5)2C2O4 wash solutions are easier to prepare and store than are the (N2H5)2CO3 solutions and (b) the and ions in spent (N2H5)2C2O4 wash solutions can be decomposed into gases, whereas the sodium from Na2CO3 solutions must eventually be stored in some form as nuclear waste.