The spatio-temporal evolution of the silicon monoxide SiO plasma produced by a high-power CO2 pulsed laser has been investigated using optical emission spectroscopy (OES) and imaging methods. The formed plasma was found to be strongly ionized, yielding Si+, O+, Si2+, O2+ and Si3+ species, rich in neutral silicon and oxygen atoms, and very weak molecular bands of SiO time-integrated and time-resolved two-dimensional OES plasma profiles were recorded as a function of emitted wavelength and distance from the target. The temporal behavior of specific emission lines of Si, Si+, O+, Si2+ and O2+ was characterized. The results show a faster decay of O2+ and Si2+ than that of O+, Si+ and Si. The Stark broadening of isolated single-ionized silicon emission lines was employed for deducing the electron density during the plasma expansion. The relative intensities of two Si2+ lines were used to calculate the time evolution of the plasma temperature.