Binary mixtures of nematic 5CB with some kind of non-mesomorphic solutes were found to cause the increase in nematic-isotropic transition temperature, contrary to usually observed decrease. "Unusual" solutes found in this work all had active hydrogen which can act as hydrogen bond donor. Admixing of methyl or ethyl substituted compounds of above solutes resulted in usual depression of transition temperature. "Unusual" increase in clearing temperature were attributed to the hydrogen bonding interaction between 5CB and solutes. The thermal effects of hydrogen bonding interaction between 5CB and various nonmesomorphic solutes were studied in detail.