The cokes with low reactivity index (CRI) and high coke strength after reaction (CSR) are generally regarded as good quality and acceptable for blast furnace (BF) operators. However, the cokes with greatly varied CRI and CSR can also be used in large BF with stable operation. Thus, it can be suggested that the CRI and CSR tests should be disputed and distrusted. In this paper, various coke-quality parameters and measurement are proposed for a good understanding of cokes with greatly varied CRI and CSR. The developed coke-quality parameters are defined as an initial temperature of coke reaction (T-i), coke reaction rate at the coke weight loss of 25% (CRR25), and coke strength after reaction (CSR25) tested by not-isothermal to isothermal or isothermal experiment. The quality parameters of cokes proposed in this study can explain the stable operation of cokes with higher CRI and lower CSR in BF. (C) 2016 Published by Elsevier Ltd.