In the paper, [Mn(C₆H₄NO₂)₂]•2H₂O (s) was synthesized and characterized by IR, elemental analysis and thermogravimatric analysis. The standard molar enthalpies of solution of [MnCl₂•4H₂O (s)], [2C₆H₅NO₂ (s)], and [[Mn(C₆H₄NO₂)₂]•2H₂O (s)] in a mixed solvent of absolute ethyl alcohol, dimethyl sulfoxide (DMSO) and 2 mol•L^－1 HCl were determined by calorimetry to be [MnCl₂•4H₂O (s), 298.15 K]＝－(13.596±0.170) kJ•mol^－1, [2C₇H₆O₃ (s), 298.15 K]＝(42.780±0.090) kJ•mol^－1 and [[Mn(C₆H₄NO₂)₂]•2H₂O (s), 298.15 K]＝(15.936±0.070) kJ•mol^－1. The enthalpy change of the reaction MnCl₂•4H₂O (s)＋2C₆H₅NO₂ (s)＝[Mn(C₆H₄NO₂)₂]•2H₂O (s)＋2HCl (g)＋2H₂O (l) was determined to be (1)＝(66.42±0.88) kJ•mol^－1. From date in the literature, through Hess law, the standard molar enthalpy of formation of [Mn(C₆H₄NO₂)₂]•2H₂O (s) was estimated to be [[Mn(C₆H₄NO₂)₂•2H₂O (s)], 298.15 K]＝－(1554.8±2.0) kJ•mol^－1. The thermokinetic properties of the action of the manganese nicotinate on growth metabolism of S. pombe were studied by means of a TAM air isothermal calorimeter at 301.15 K. The microbial growth rate constant k, the values of the peak time t_p and the total thermal effects Q_total, were obtained, respectively. Experimental results show that the k and Q_total values of S. pombe decreased with the increase in the concentrations of the niacin manganese and the compound has good inhibition action on the growth of S. pombe.

Key words: manganese chloride tetrahydrate, nicotinic acid, microcalorimetriy, standard molar enthalpies of formation, S. pombe