Ru(III) catalyzed Oxidation of dimethyl diethylene glycol (DMDG) by potassium bromate in acidic media in the presence of mercuric acetate shows zero order dependence on dimethyl diethylene glycol [H+] ions while it is first order for [bromate] and Ru(III). Addition of mercuric acetate has no effect on the reaction. The real reactive species of Ru (III) chloride has been proposed as (RuCl2(H2O)4]+ in the acid range. The reaction product is the corresponding aldehyde. Various activation parameters have been computed.