The solubilities of isobutane (R600a) in pentaerythritol tetrapentanoate (PEC5) and in pentaerythritol tetraheptanoate (PEC7) between (293.15 and 348.15) K have been measured based on the isochoric saturation method. The experimental solubility data were correlated by using the Peng-Robinson equation of state with the LCVM mixing rule in which the excess Gibbs energy at infinite pressure was represented by the van Laar equation. The absolute average deviation and maximum absolute deviation of the pressure from the correlated results was 1.18 % and 3.27 % for R600a + PEC5 system, respectively. For the R600a + PEC7 system, the absolute average deviation and maximum absolute deviation of pressure was 0.92 % and 2.17 %.