[Ru(η2-O2CO)(pta)(η6-p-cymene)] (1) was isolated and characterized. 1 is a highly active new Ru(II)-catalyst of redox isomerization of allylic alcohols. 1 is significantly more active than the in situ [RuCl2(P)(η6-arene)] + base catalysts. 1 is able to catalyze allylic alcohol transposition in neutral aqueous systems. Solid state structure of 1 was determined by single crystal X-ray diffraction.