The term “overdriven detonation” refers to detonation process in which the main detonation parameters, such as detonation pressure and propagating velocity, exceed the corresponding Chapman-Jouguet (C-J) values. This kind of detonation state can be realized by the impingement of a high velocity object upon the explosive. This paper presents our initial survey on the occurrence of overdriven detonation in high explosive. The HMX-based PBX is used to accelerate the metal plate being used as the impactor. The target explosive is the so-called SEP, simplified from the term of the ‘safety explosive,’ with the composition of PETN wt.65&percent; and paraffin 35 wt.&percent;. By changing the thickness of the metal plate under an unvaried amount of donor explosive, the different impinging velocities are yielded. The propagation of the detonation wave grown from the impingement of metal plate is recorded by the high-speed streak camera owing to the self-luminosity of detonation. The higher detonation velocity is found from the experimental results. Meanwhile, the impacting velocities of the metal plate are determined by one-dimensional Lagrangian numerical method enabling to estimate the initial input pressure into the target explosive by the impedance matching method. The obtained input pressures are of larger values than the C-J pressure. ©2000 American Institute of Physics.