An aqueous polishing composition comprising (A) at least one water-soluble or water-dispersible compound selected from the group consisting of N-substituted diazenium dioxides and N-hydroxy-diazenium oxide salts and (B) at least one type of abrasive particles the use of the compounds (A) for manufacturing electrical, mechanical and optical devices and a process for polishing substrate materials for electrical, mechanical and optical devices making use of the aqueous polishing composition.