The catalytic efficacy of different cesium salts of 12-tungstophosphoric acid as nanocatalysts was checked in Claisen-Schmidt condensation of aldehydes and ketones under solvent-free conditions to produce chalcones. The reaction is fast and environmentally benign with excellent selectivity for the synthesis of chalcones. Results of potentiometric titration and catalytic reactivity of the catalysts indicated that the catalytic reactivity should be directly proportional to the strength and number of the surface acid sites, are the ones accessible to the reactants. Reusability of the catalysts and acidic properties of reused catalysts were investigated. Coking could cause a loss in catalyst acidity, leading to a decrease in the product yield. But the amount of coke remains constant in successive runs. Furthermore, the use of this catalyst is feasible because of its easy preparation and handling, and stability. Large-scale synthesis is also beneficial in this method. Two new compounds are synthesized and fully characterized.