This book intends to identify some new polymer composites with polyester matrix and graphene and their mechanic characterization. Why polyester? Polyester raisin is one of the most used polymere material in all industries. The advantages of the polyester are: low price, good mechanical strength, low density, UV resistance, acid resistance, hydrophobia. The main disadvantage is that polyester cannot be recycled. Why graphene oxide? Because during the last years there have been discovered simpler methods of obtaining it and the development of technology allows easier testing of graphene oxide. Graphene oxide is considered to be one of the strongest materials on the planet, which has very good tribologic and thermal properties. Graphite was chosen as reference for graphene oxide, because graphene is the elementary carbon atoms layer in the composition of the graphene. Graphite is, in fact, a superposition of graphene layers. The objective/ aim of the current thesis is to develop a new class/ cathegory of graphene polymer composites and their tribologic, thermal and mechanical character.