Please cite this article as: Morschhauser, A., Grott, M., Breuer, D., Crustal recycling, mantle dehydration, and the thermal evolution of Mars, Icarus (2010), doi: 10.1016/j.icarus.2010 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.Crustal recycling, mantle dehydration, and the thermal evolution of Mars Mars would then be driven by the extraction of a primordial crust after core formation, cooling the mantle to temperatures close to the peridotite solidus. According to this scenario, the second stage of global crust formation took place over a more extended period of time, waning at around 3500 Myr b.p., and was driven by heat produced by the decay of radioactive elements. Present-day volcanism would then be driven by mantle plumes originating at the core-mantle boundary under regions of locally thickened, thermally insulating crust. Water extraction from the mantle was found to be 1 relatively efficient and close to 40 percent of the total inventory was lost from the mantle in most models. Assuming an initial mantle water content of 100 ppm and that 10% of the extracted water is supplied to the surface, this amount is equivalent to a 15 m thick global surface layer, suggesting that volcanic outgassing of H 2 O could have significantly influenced the early Martian climate and increased the planet's habitability.