Spent V catalyst from SO2 oxidn. was leached with aq. soln. of NaOH to remove Fe, Cu, Zn, As and Pd and to recover the catalyst-contained V and K. After leaching under optimum conditions (temp. above 303 K, leaching time longer than 2 h, NaOH conc. 10% by mass, catalyst size below 750 mu m, solid-liq. ratio above 1:15), the recovery degree were 90% for V and 99% for K.