The diploma thesis deals with solving weight problem in hydraulics cylinder for mobile hydraulics, by incorporating carbon polymers. Thesis covers parts design, analysis of non-standard parts and testing complete assembly of hydraulic cylinder. For testing, we choose a hydraulics cylinder with dimensions 40 mm /22 mm x 305 mm, and we used mineral hydraulics oil ISO VG46. All of the testing was done in Laboratory for fluid power and controls. Base parameters for test were system pressure up to 60 MPa and the total movment of 100 km for long term durability testing. Analasis of the non standard parts showed they would endure the stresses posed by the pressure and that the carbon-fiber cylinder should hold pressure load. While we where testing for maximum load we learned that the current structure of carbon-fiber cylinder could not hold the pressure load. To achive bigger pressure loads, further development of carbon-fiber tube would be needed.