Vapor pressure was measured for the quasi-binary section Cd1-xZnxTe of the phase diagram of the ternary system Cd-Zn-Te with x = 0.10 and 0.15. From this experiment, P-T-X (pressure-temperature-composition) space arrangement of the solidus was derived, and the vapor pressure scanning method was applied for high-precision determination of non-stoichiometry in Cd(0.9)Zi(0.1)Te(1 +/-delta) and Cd(0.85)Zn(0.15)Tel(1 +/-delta). The solidus volume was shown to be of pronounced asymmetrical shape with retrograde Te solubility. The stoichiometric 50 at% Te plane is contained in the Cd0.9Zn0.1Te1 +/-delta solidus volume, while being completely outside the Cd0.85Zn0.15Te1 +/-delta solidus, on the metal side of it. Phase equilibrium is presented in T-X and P(i)-T projections (i = Cd, Zn, Te,) of the phase diagram. These data are crucial for preparation technology of Cd1-xZnxTe1 +/-delta with strictly controlled composition and for high-precision analysis of the matrix elements. From the isoplethal (X-s = const) sections of the solidus, partial sublimation enthalpies of the main vapor species were estimated. (c) 2005 Elsevier B.V. All rights reserved.