Temperature dependence of partial molar volume of 4-amino-4'-nitrobiphenyl (ANB) and 4,4'-dinitrobiphenyl (DNB) in the isotropic phase of 4-n-pentyl-4'-cyanobiphenyl (5CB) was determined. Addition of ANB to 5CB causes increase of isotropic-nematic phase transition temperature (T-IN) [1]. The decrease of partial molar volume of ANB was observed while the increase of partial molar volume of DNB and triphenyl phosphite (TPP) [8] was observed with approaching T-IN. The anomalous behavior of partial molar volume was discussed using treatments similar to that of other thermodynamic derivatives in the I-N transition. (C) 2011 Elsevier B. V. All rights reserved.