Spent industrial V catalysts from SO2-to-SO3 oxidn. were leached with aq. urea soins. to recover V and Fe at varying catalyst grain size (0.09 to 0.50 mm), urea concn. (10 and 40%) and leaching time (0.5 to 2 h). The initial concns. of V and Fe (as V2O5, and Fe2O3) in the spent catalysts were assumed 5% and 1.65%, resp. The V concn. in the leachates (as V2O5) increased from 3.528 up to 4.429 g/L with decreasing catalyst grain size and increasing urea concn. and leaching time. The Fe conc. (as Fe2O3) increased from 0.331 up to 0.706 g/L, resp.