In the present study the effect of low-pressure vacuum plasma and cold atmospheric pressure plasma surface treatments of polypropylene samples with 12% of talc addition substrates is analysed in order to find an efficient procedure which is able to increase the adhesion with a polyolefin hot-melt adhesive typically used in automotive industry. The polymeric substrates were treated at first using different plasma gas mixtures and varying some process parameters such as power and working distance of the jet in order to find the most suitable configuration considering the process gas to be used. Once identified the most effective plasma treatment for both low-pressure and atmospheric pressure plasma treatments, a deeper and more precise analysis of the process is carried out, taking into account both the chemical and mechanical effect of plasma on bonded joints and on the polymeric substrates.