We explore the effects of cation off-stoichiometry on structural, electrical, optical, and electronic properties of CoâZnOâ normal spinel and CoâNiOâ inverse spinel using theoretic and experimental (combinatorial and conventional) techniques, both at thermodynamic equilibrium and in the metastable regime. Theory predicts that nonequilibrium substitution of divalent Zn on nominally trivalent octahedral sites increases net hole density in CoâZnOâ. Experiment confirms high conductivity and high work function in CoâNiOâ and Zn-rich CoâZnOâ thin films grown by nonequilibrium physical vapor deposition techniques. High p-type conductivities of CoâZnOâ (up to 5 S/cm) and CoâNiOâ (up to 204 S/cm) are found over a broad compositional range, they are only weakly sensitive to oxygen partial pressure and quite tolerant to a wide range of processing temperatures. In addition, off-stoichiometry caused by nonequilibrium growth decreases the optical absorption of CoâZnOâ and CoâNiOâ thin films, although the 500-nm thin films still have rather limited transparency. All these properties as well as high work functions make CoâZnOâ and CoâNiOâ thin films attractive for technological applications, such as hole transport layers in organic photovoltaic devices or p-type buffer layers in inorganic solar cells.