Photoluminescence and infrared absorption in liquid encapsulated Czochralski‐grown InP single crystals are discussed. Photoluminescence intensities, intensity ratio, and half‐width due to donor‐valence band and conduction band‐acceptor transitions are clarified at 77 K as functions of carrier concentration. Acceptor binding energies of Zn, Cd, and Hg impurities are determined. Correlations between free‐carrier absorption coefficient and carrier concentration to mobility ratio are also examined. It is concluded that carrier concentration, compensation ratio, and mobility in InP single crystals can be determined nondestructively by combining their photoluminescence and infrared absorption spectroscopies.