Solvent-free synthesis of isobenzofuran-1(3H)-ones have been described via reaction of phthalaldehydic acid (2-carboxybenzaldehyde) with methylaryl or cyclic ketones using sulfuric acid immobilized on silica (H2SO4-SiO2) in excellent yields (70-88%). The catalyst can be recovered by simple filtration and reused. Also, some of these compounds has been studied the third-order nonlinear optical properties by laser Gaussian z-scan techniques.