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International audience; Thanks to its high degree of crystallinity, polyoxymethylene (POM) homopolymerexhibits high mechanical properties of strength, stiff ness and creep. In the case ofPOM copolymer, the strength and stiff ness are slightly lower because of its lowerdegree of crystallinity. Furthermore, the use domain ranges from -30°C to 150°Cwhich allows various applications. More specifi cally to the POM, friction propertiesare excellent due to oxygen contained in the POM monomer.Th e major drawback of POM homopolymer is its brittleness at RT compare topolyolefi ns, typically nominal strain at break values are close to 20%. To improvemechanical properties at failure, diff erent strategies can be adopted as POM copolymerhave lower crystallinity degree (strain at break close 70%) or added polyurethanein POM matrix (100ST from DuPont for instance). However, we will seethat these strategies lead to a decrease in the material’s stiff ness. Lastly, anotherpossible way is the use of specific processing conditions to induce oriented morphology.We will review all these aspects.This chapter is divided in two major parts: the first part is devoted to shorttermmechanical properties as elastic properties as a function of temperature andmorphology aspects, failure properties and the diff erent strategies to improvethem. The second part aims to present long-term properties such as creep behaviorand modifi cations induced by aging, leading to an embrittlement of the POMlimiting its lifetime.