The effect of solvent type on the molecular size and intermolecular interaction of triglyceride was investigated by the intrinsic viscosity technique. Both the indices may be important for discussing and scrutinizing the behavior of homogeneous transesterification of triglyceride with alcohol since it was found that the co-solvent type influences both the transesterification rate and hydrodynamic size of triglyceride in a homogeneous system. Kinematic viscosity of palm oil dissolved in six different solvents was measured at 298 K by using glass capillary type viscometer to determine the intrinsic viscosity and Huggins constant. By plotting the intrinsic viscosity and Huggins constant against the seven physical properties of the solvents, the polarity of the solvent has been identified as the key factor for molecular size of triglyceride in solution. On the contrary, none of the seven physical properties showed good correlation with the Higgins constant. This may be attributed to more complex nature of the Huggins constant in comparison with the intrinsic viscosity. © Published under licence by IOP Publishing Ltd.