A transitiometric method for determining isobaric thermal expansivity of liquid 1,4-dichlorobutane and 1-bromo-4-chlorobutane as a function of temperature and pressure through calorimetric measurements against pressure is described. Isobaric thermal expansivities of haloalkanes were determined over the temperature range from 273.15 to 423.15 K at pressures up to 200 MPa. Experimental results were used to model the general density scaling-based equation of state and to analyze the pressuretemperature behavior of the thermal expansion coefficient. We confirmed that investigated liquids present a characteristic pressure range in which (partial derivative alpha(P)/partial derivative T)(P) = 0.