The electronic band structure, metallization, structural phase transition and superconductivity of cubic zinc blende-type GaP and GaN are investigated. The equilibrium lattice constant, bulk modulus and pressure at which the compounds undergo a structural phase transition from ZnS structure to NaCl structure are predicted from the total energy calculations. The density of states at the Fermi level (N(E F )) is enhanced after metallization, which leads to the superconductivity in GaP and GaN. The superconducting transition temperatures (T c ) of GaP and GaN are obtained as a function of pressure for both the ZnS and NaCl structures and GaP and GaN come under the category of pressure-induced superconductors. When pressure is increased T c increases in both the normal and high-pressure structures. The dependence of T c on the electron-phonon mass enhancement factor λ shows that GaP and GaN are electron-phononmediated superconductors. Also, it is found that GaP and GaN retained in their normal structure under high pressure give appreciably high T c .

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