This paper deals with a new, quasi-isothermal method for the measurement of heat capacity in an LKB 2277 heat flow microcalorimeter TAM (thermal activity monitor), following the calibration principle. The specific heat capacity of a specimen of any material (liquid, solid, bulk, inhomogeneous, etc.) which fits into a 4 ml sample cup can be determined with an uncertainty of less than 5%. With a quasi-isothermal method no heating up or cooling down of the calorimetric unit is needed. The temperature of the thermostat represents directly the test temperature.