AcMe and AcPh were condensed at 30 degrees C or 60 degrees C, resp., in ultrasound field (20 kHz) in a glass reactor (80 ml) or in a microwave field (2.46 GHz) in a teflon reactor (100 ml) in presence of alkaline catalyst (MgO, NaOH, KOH, KOH/Al2O3) or acidic catalyst (Amberlyst 15, AlCl3) for 10 min to obtain diacetone alcohol or dypnone isomer, resp. Mesityl oxide, a-isophorone, mesitylene and oligomers were found in the product of AcMe condensation, whereas dypnone (cis- and trans-isomers) and oligomers were found in the product of AcPh condensation (without ultrasounds). No traces of any aldol were identified in the reaction product of AcPh condensation. The reactions were modelled by the B3LYP/6-31G* method. Reaction mechanism was proposed.