A scientific and technical solution of capillary calorimetric unit design is described based on a method of separating the sensitive volume of calorimetric cells with a heat-conducting bridge in a differential titration calorimeter. The design of the calorimetric cells as thin capillary tubes allowed to minimize the dimension of the heat-conducting bridges and to separate with high accuracy the sensitive volume of the calorimetric cells which is of 78.5 μl. Due to high calorimeter power sensitivity (10 nW) a modern level of requirements for measuring minimum specific heat of processes is provided. The adopted design of the calorimetric cells permits to possess the cells located horizontally and to simplify the solution of the problem of equalizing components concentration along the volume of the calorimetric cells.