An adiabatic drop-calorimeter was used to measure changes in the enthalpy H-0(T)-H-0(T-b) of hypoeutectic Al1-xSix alloys (with Si concentrations x = 0, 1.92, 6.26, and 9.22 wt %) and of the commercial cast alloy AL5M (x approximate to 5.0 wt %) in a temperature range of 350-1200 K relative to the "basis" temperature T-b = 293.15 K. Based on the experimental data obtained, heat capacities of Al1-xSix alloys in the solid state were calculated.