A double base propellant is a polymer which is used as an energetic material to propel rockets. Advances in computers are making it possible to simulate a rocket as a whole, i.e. structurally and thermally. Among the rocket elements, little literature exists regarding the thermal and mechanical properties of propellants at a specified environment. In this study, a double base propellant is produced and then characterised. Accordingly, tensile specimens of the propellant are prepared according to JANNAF specifications to determine its mechanical properties. The tests are carried out at a possible 74 degrees C and also at varying crosshead speeds of 1.3, 6 and 30 mm min(-1). As of the thermal properties, the heat conduction coefficient, the specific heat and the density have been determined. All these properties complete the basic data for a thermomechanical simulation of a rocket on computer.