The products of cobalt manganese oxyhydroxide (Co III 9Mn IV 3O26H13, denoted as CMOH) have been shown to be a highly continuous film with a thickness as small as tens of nanometers, enabling high transparency with full surface coverage. The acidic nature of the reaction mixture avoids the occurrence of alkaline precipitation. The oxidant MnO4 -is most likely to perform a rapid corrosion on the substrates to gain strong adhesion. Meanwhile, the oxyhydroxide layer formation behavior has been observed to be dependent on the counter-anions of the metal precursors, where the mechanism studies show a self-limiting role of acetate anions during the film growth. Hence, the usage of acetate as the counter-anion of the Co precursor should enable regulation on the film thickness for the high transparency purpose.