The isobaric heat capacities of boric acid solution are crucial for the design of boron recovery systems in nuclear power plants. In this work, the isobaric heat capacities of boric acid solution containing 0.648 mol/kg and 3.700 mol/kg 10B from T/K = (303.16 to 394.25) and up to 5.11 MPa are measured with a flow calorimeter. The expanded uncertainties in temperature, pressure, and isobaric heat capacity were +/- 0.02 K, +/- 3.20 kPa, and +/- 0.0098, respectively. The isobaric heat capacity of boric acid solution decreases when the 10B concentration and pressure increase, and increases as the temperature increases. A correlation equation is presented for the isobaric heat capacities of boric acid solution, the absolute relative deviation between the correlation and experiment is less than 0.6 %.