The generation of fast particles (both ions and electrons) in a femtosecond laser-produced plasma has been studied experimentally and the possibility of applying particle-in-cell (PIC) codes to the description of the experimental results has been investigated. The energy distribution function of fast ions has been measured directly by means of X-ray spectroscopy. It is shown that this diagnostic can also be used as an indirect method to measure fast electrons inside the plasma. The hot electron distribution in the 0.1–2 MeV energy range was measured directly using a standard electron magnetic spectrometer. The comparison of the experimental results with the numerical simulations show: (1) the electromagnetic PIC-FC code can be successfully applied for simulating plasmas created by the interaction of femtosecond-laser pulses with solid targets and (2) the existence of a transient population of hot electrons with a non-Maxwellian distribution typical of interaction experiments with short-pulse lasers.