  Recent developments of the AC-calorimetric technique adapted for the needs of
high pressure experiments are discussed. A semi-quantitative measurement of the
specific heat with a Bridgman-type of pressure cell as well as a diamond anvil
cell is possible in the temperature range 0.1 K < T < 10 K. The pressure
transmitting medium used to ensure good pressure conditions determines to a
great extent via its thermal conductivity the operating frequency and thus the
accessible temperature range. Investigations with different pressure
transmitting media for T > 1.5 K reveal for solid He a cut-off frequency which
is considerably higher than for steatite. Experiments below 1 K and pressures
above 10 GPa clearly show that the pressure dependence of the linear
temperature coefficient of the specific heat can be measured. It is in
qualitative agreement to a related quantity obtained quasi-simultaneously by
electrical resistivity measurements on the same sample.
