Optical emission lines from the plasma generated by a laser ablation process have been investigated to gather information on the nature of the chemical species present. In particular, the experiments were carried out during the laser ablation of a ZnMnO target, in presence of a controlled oxygen atmosphere. The resolved emission spectra are dominated by the atomic neutral or singly ionized emission lines from Zn species, while the Mn I line was detected in emission spectrum at 40 mTorr only. The background continuum, intensities and widths of all observed lines increased with increasing gas pressure. The electron density and electron temperature were calculated for various gas pressures. The electron density was found to increase with the increment of the argon gas pressure, whereas electron temperature decreased. The electron temperature and density are found to be similar to those obtained in the well-known pulsed laser deposition (PLD) process.