Oil and gas produced from organic-rich shales have become in the last ten years one of the most promising sources of unconventional fossil fuels. The oil and gas are trapped in rocks of very small permeability, but hydraulic fracturing enables to operate those reservoirs with competitive costs. The global reserves of shale oil and gas that are potentially recoverable are equivalent to tens of years of world con- sumption. However, hydraulic fracturing is facing many challenges regarding the productivity but also the security and the environment. One of those challenges is to un- derstand how the fractures propagate underground. The propagation depends on the mechanical stress prevailing in the reservoir and on the fracture properties of the rocks. Regarding the fracture properties, the oil and gas indus- try developed brittleness indicators to distinguish between brittle rocks (containing mostly calcite and silica) and duc- tile rocks (containing a significant proportion of clay and kerogen). During fracturing, a brittle rock shatters easily leading to a well-distributed network of fractures, whereas a ductile rock deforms instead of shattering leading to few fractures and in some situations acting as a barrier to the fracture propagation. In this work, we study the role of kerogen in the ductility of shale. The ultimate objective is to develop a fine understanding of the fracture properties of shales.