The measurements of isobaric heat capacity for isobutane were carried out using a flow calorimeter in both compressed liquid and supercritical phase. 250 data of heat capacity were obtained at the temperature range from 303 K to 413 K at pressures up to 12 MPa. The relatively expanded uncertainty in the heat capacity measurement was estimated to be less than 1% with k = 2 (95%). An empirical equation was correlated to represent the experimental values with an average absolute deviation of 0.7%. In addition, the saturated liquid heat capacities of isobutane were also derived by extrapolating the empirical equation to the corresponding saturated pressure. (C) 2017 Elsevier Ltd.