In this manuscript, we have reported first time the densities, q, speeds of sound, u, and refractive indices nD for pure 1-alkyl-3-methylimidazolium bromide [C(n)mim][Br] (n = 4, 6 and 8), poly ethylene glycol 400 and their binary mixtures at 0.1 MPa, covering entire range of compositions and temperature ranges from 293.15 K to 323.15 K. The measured properties have been used to derive excess molar volumes, V-m(E), excess molar isentropic compressibilities, K-s,m(E), and refractive indices deviation, Delta(empty set)n(D). The values of V-m(E), K-s,m(E) and Delta(empty set)n(D) have been fitted to Redlich-Kister polynomial equation for evaluation of binary coefficients. The variation in excess properties have been discussed in terms of hydrogen bonding and ion-dipole interaction. The V-m(E) and K-s,m(E) were largely negative and decrease with increasing temperature and size of alkyl chain of ionic liquid. The Delta(empty set)n(D) is small negative. The experimental n(D) of the binary mixtures were predicted by several mixing rules. The experimental V-m(E) were reviewed by Prigogine-FloryPatterson (PFP) theory and Extended real association model (ERAS). (C) 2016 Elsevier Ltd. All rights reserved.