We report an analytic expression that accurately represents the dielectric functions epsilon= epsilon 1+ i epsilon 2 from 1.5 to 6.0 eV of InAsxP1 - (x) alloy films over the entire composition range 0 <= x <= 1. We use the parametric model ( PM), which describes the dielectric functions of semiconductor materials as a sum of Gaussian- broadened polynomials. The dielectric function spectra are those that we obtained previously by spectroscopic ellipsometry for the specific compositions x = 0.00, 0.13, 0.40, 0.60, 0.80, and 1.00. The PM reconstructions are in excellent agreement with the data. With the information provided here, dielectric functions of arbitrary compositions can be calculated. (C) 2014 Elsevier B. V. All rights reserved.