 In 1853 he was named member of the archdiocesan Chapter and two years later he was named auxiliary bishop of Milan and titular bishop of Famagosta.In 1859 archbishop Romilli died and the chapter of the cathedral named Caccia Dominioni as diocesan administrator during the vacancy of the see.For the succession to archbishop Romilli Caccia Dominioni was one the candidate but pope Pius IX chosen with the advice of Austrian Emperator the more conservative Paolo Angelo Ballerini the vicar of archbishop Romilli.