The vapour liquid equilibrium (VLE) behaviour of the quaternary system, Methanol (1) + Isopropyl alcohol (IPA) (2) + Water (3) + Glycerol (4) at 53.33, 66.66, 79.99 and 95.2 kPa, has been studied experimentally using a Sweitoslawsky-type ebulliometer. The VLE data of this quaternary system at subatmospheric and ambient conditions will be useful in the process intensification design of bio-diesel production. Experimental VLE data were compared with predictions from Wilson and NRTL models using only the constituent binary interaction parameters. The predictions of equilibrium temperatures thus obtained using Wilson model compared well with the experimental values with an average root mean square deviation (rmsd T) of 03153 K. The binary system IPA (2) + Glycerol (4) was studied experimentally at 5333, 66.66, 79.99 and 94.93 kPa and the data correlated with Wilson, NRTL, UNIQUAC and Peng-Robinson (PR) and Soave Redlich-Kwong (SRK) equations of state (EoS) combined with Wong -Sandler (WS) mixing rules. Experimental data of this binary system was also compared with predictions from UNIFAC model. The VLE data of the binary system IPA (2) + Water (3) at 94.66 kPa is reported here and correlated with Wilson and NRTL activity-coefficient models. Wilson model represented the binary systems better than other models with a mean rmsd Tot 0.2853 K for IPA (2) + Glycerol (4) and an rmsd T of 0.1390 for the IPA (2) + Water (3) system. MATLAB programming has been used for all the calculations. (C) 2015 Elsevier B.V. All rights reserved.