Photofission reactions are used for various applications ranging from the evaluation of fundamental nuclear data to the characterisation of radioactive waste packages, including homeland security and counter-proliferation. Due to the photon flash emitted at each pulse delivered by an electron accelerator and the resulting saturation of the detectors and electronics during a few milliseconds, prompt neutron detection is currently not deployed. Photofission methods are currently based on the detection of delayed neutrons and gamma-rays. However, so-called "indirect" techniques aiming at activating a radionuclide and then measuring its decay would allow access to the signal of prompt neutrons, representing about 99% of photofission neutrons. The objective of this thesis is to develop a system for the detection of prompt neutrons from photofission around an electron accelerator. Following a state of the art, the first axis of research will consist in designing the detection system based on Monte Carlo simulations. The second axis will aim to experimentally evaluate and validate its measurement performance with uranium and plutonium samples. Finally, the third axis will investigate the combination of the prompt neutron signature with the delayed neutron and gamma signatures in order to reduce the uncertainties relating to the identification of radionuclides within an object to be inspected.