In this study, a new experimental design, which has the advantage of estimating simultaneously the three components of the thermal conductivity tensor and the specific heat of orthotropic polymer composite materials, is presented. Furthermore, no sample instrumentation is required, reducing substantially the global experimental procedure duration. The measurement technique consists in dissipating a known heat flux thanks to a home-designed thin heater, composed by two distinct heating elements and sandwiched between two cylindrical samples. The heater is also used as measurement instrument since micro-thermocouples are incorporated inside. The parameter estimation is performed by solving an inverse heat conduction problem. The method has been validated on a sample with known properties. The thermal properties of a unidirectional carbon-fiber composite have been then characterized. The results, obtained from a two-step estimation strategy are in good agreement with those determined within the framework of round-robin test.