New laboratory tests have been developed to characterise the coke behaviour at high temperature under conditions similar to those encountered in the blast furnace, especially in terms of gasification degree. The validity of these new tests has been demonstrated by comparison with the modifications undergone by coke in the blast furnace. The latter have been determined by comparing cokes sampled by a tuyere probe with cokes sampled before charging. The results showed only little correlation with the classical coke characterisation indices (I10, I40, CSR), which indicates that they really bring new information on coke properties.