In this work, a novel and simple method was put forward to measure the isobaric specific heat capacity for the kerosene RP-3 with a flow-calorimeter at the conditions of high temperature and high pressure. Based on the energy conservation principle, the formula for heat capacity was derived and its measurement was realized by the convective mixing method between the hot and cold fuel. Taking the precision of the instrument and the error transfer into account, the relative expanded uncertainty of this method was acquired of about +/- 6.38% (coverage factor k=2). Meanwhile, the accuracy and reliability were verified by the standard material of water and n-decane. In the temperature range from (296.2-719.0) K and under pressure range from (2.4-4.0) MPa, the measurement for the kerosene RP-3 was carried out and the experimental observations were compared and agreed well with the published data. At last, an empirical correlation relationship of heat capacity due to the temperature and pressure was presented by using Garg's model with the measured experimental data. (C) 2016 Elsevier B.V. All rights reserved.