Abstract: A zirconia-based coating composition comprising a mixture obtained by mixing:(a) at least one compound selected from the group consisting of (a') a zirconium compound represented by the general formula (I):Zr(OR).sub.4 (I)wherein R is an alkyl group having 2-5 carbon atoms or the general formula (I'):Zr(OR).sub.4.ROH (I')wherein R has the same means as defined above, (a") a partial hydrolyzate of the zirconium compound (a'), and (a'") a partial condensate of the partial hydrolyzate (a"),(b) a .beta.-diketone or .beta.-ketoester represented by the general formula (II):R.sup.1 COOH.sub.2 COR.sup.2 (II)wherein R.sup.1 is an alkyl group having 1-5 carbon atoms, R.sup.2 is an alkyl group having 1-5 carbon atoms or an alkoxy group having 1-4 carbon atoms),(c) water, and(d) a hydrophilic organic solvent.