This paper is devoted to solving problems related to calculation of friction coefficient in friction pair of pneumatic elements in mechatronic systems, by taking into account adhesion forces and verification of theoretical expressions with experimental results. The most important factor, which influences the wear behaviour of these friction pairs, is surface roughness of friction surfaces. A theoretical calculation of friction coefficient allows us to find the optimal surface roughness parameters, which will suite the requirements of service life of pneumatic cylinders used in factory automation applications.