Catalyzed　by　10　mol-%　PhCO2H,　the　[3+2]　cycloaddition　between　3-isothiocyanato　oxindoles　and　nitroso　compounds　proceeded　readily　to　deliver　1,2,4-oxadiazolidine-3-thione-fused　spirooxindoles　in　40-82　%　yield.　The　structures　of　the　title　compounds　were　firmly　confirmed　by　X-ray　single-crystal　structure　analysis.