Knowledge of the mechanical properties, i.e. strength, stiffness and deformation capacity, of cementitious materials at any arbitrary time is fundamental for operations such as removal of formwork, prestressing or cracking control. This paper presents a study of the evolution of indexes related to hydration and their correlation to the development of the mechanical properties for an Ultra-High Performance Fiber Reinforced Concrete (UHPFRC). The hydration kinetics was determined using semi-adiabatic heat of hydration tests, and the mechanical properties were investigated experimentally at several ages between 3 and 365 days and then described with models originally developed for conventional concretes. Models and experiments were in good agreement. Furthermore, it was observed that for the UHPFRC, the rate of development of mechanical properties was highest for the secant modulus, followed by the compressive and then the tensile strength.