The hydrothermally deposition process for applying zirconia coating onto metal substrates was studied at different conditions to understand better the interfacial chemistry of the coating formation. In this study, a new non-recirculating autoclave coating system, incorporating the precursor-supply-system, which delivered the solution with constant concentration, was designed. A number of operating parameters (temperature, pH of aqueous solution, oxidant concentration, solution hydrodynamics, and duration of deposition process) have been investigated in terms of their effect on the deposition of ZrO2 films. The coating quality was analyzed. The process window for formation of adherent coating appeared to be relatively narrow: solution temperature 190-200 °C, the pH of the aqueous reservoir 5.3-7.5. Oxidant concentration affected coating adhesion rather than coating formation.