Commercially available potassium hydroxide (KOH), a simple base, was found to be a catalyst for tandem cross-aldol condensation between cyclic ketones and aromatic aldehydes leading to a fast and easy synthesis of α,α-bis (substituted-arylidene) cycloalkanones in the shortest times of all previous methods. The reaction of aryl aldehydes with five and six-membered cyclic ketones afforded excellent yields after few seconds in most cases. The reaction conditions were compatible with various electron withdrawing and electron donating substituents, e.g. Cl, F, NO2, OMe, Me and NMe2.