Activity of 20wt% MO2/Al2O3 catalysts, where M = Mn, Ce and Zr has been studied in ketonisation of the mixtures of propanoic/pentanoic, ethanoic/10-undecenoic and hexanoic/(Z)-9-octadecenoic (oleic) acids. Irrespective of the molecular weights and molar ratios of reacting acids, high yields of ketones were obtained over Mn and Ce oxide catalysts at approximately 673 K. Isomerization of C=C double bonds and partial pyrolysis occurred during catalytic ketonization of 10-undecenoic and oleic acids, diminishing slightly the yield of ketones. The preparation of (Z)-14-tricosen-6-one has been performed, being the starting material for the synthesis of (Z)-9-tricosene - sex attractant of male house fly.