In this work, we investigated the properties of an atmospheric pressure plasma jet (APPJ) generated using a \(\mathrm {Ar-H_2}\) gas mixture. For this purpose, electrical, thermal, and optical characterization were employed to obtain discharge power and current, gas temperature ( \(T_g\) ), rotational and vibrational temperatures ( \(T_r\) and \(T_v\) , respectively), electron density ( \(n_e\) ), and chemical species formed in the gas phase of the plasma jet. All parameters were analyzed as a function of the \(\mathrm {H_2}\) content in the gas mixture, for two different kinds of targets (a conductor and an insulator). Notably, large differences in discharge power, \(T_g\) , \(T_r\) , \(T_v\) and \(n_e\) were found with and without \(\mathrm {H_2}\) in the gas composition. Additionally, as an example for the \(\mathrm {Ar-H_2}\) gas mixture application, surface modification of a polymer was performed. As a result of the \(\mathrm {H_2}\) addition, there was a slight improvement in the polymer surface composition compared to the condition without hydrogen.
