Electrical properties of silicon nanoparticles (Si-np’s) embedded in a silicon oxide matrix were studied using MOS-like structures. Si-np’s were created after silicon rich oxide (SRO) films were thermally annealed at 1100 ºC. Capacitance–voltage (C–V) characteristics showed downward and upward peaks in the accumulation region. Current–voltage (I–V) measurements exhibited current valleys and downward and upward peaks. Current versus time (I–t) measurements were also done at a negative constant gate voltage. A switching behaviour between two current states (ON and OFF) was observed. These effects have been related to the charge trapping and de-trapping of the Si-np’s embedded in the SRO films.