The structural, electronic, optical and thermal properties of ternary transition metal boride (CrAlB) are studied using full potential linearized augmented plane wave method in the framework of the density functional theory. The exchange-correlation potential is solved using the modified Perdew-Burke-Ernzerhof generalized gradient approximation (PBEsol-GGA). The structural parameters are optimized to obtain equilibrium lattice constant, bulk modulus and its pressure derivative. The calculated band structure, density of states and electronic charge density show that the material possesses metallic nature and have covalent band character. Optical spectra calculations such as the real and imaginary part of dielectric constant, refractive index, extinction coefficient, reflectivity, absorption coefficient, conductivity, and loss function are performed within the photon energy range of 0-40 eV. In this case the obtained plasma frequency corresponds to 24.12eV. For radiation above this energy the property of CrAlB changes from metallic to dielectric. The calculations of the thermal properties using Gibb's program have been performed in the range 0-5000 K at 0, 20 and 50 GPa of pressure. The studies of optical and thermal properties show that it is an eligible candidate for optoelectronic devices, and the devices working at high temperature. The results for CrAlB are reported for the first time as neither CrAlB has been synthesized nor any theoretical calculation has been performed till so far. (C) 2018 Elsevier B.V. All rights reserved.