A ruthenium-catalyzed 1,4-addition of organoboronic acids to alpha,beta-unsaturated ketones has been developed. The use of 2-(di-tert-butylphosphino)biphenyl as the ligand in combination with [RuCl2(p-cymene)](2) complex catalyzes these reactions to selectively give 1,4-adducts in good yield by effectively suppressing Heck-type and reduced products.