In Andalusia (Southern Spanish region), olive industry presents a high potential of solid biofuel production because of residues generated from olive groves and those by olive oil industries. In this region, 25% of residual biomass is produced by olive sector and olive stone residues are among the most important since its production is over 450,000 tons/year. The objective of this research is to provide unambiguous and clear classification principles for olive stone residues based on their quality parameters, to serve as a tool to enable efficient trading of this biofuel and to achieve good understanding between seller and customer as well as to facilitate communication with equipment manufacturers. For this purpose, a total of 176 olive stone samples from 71 different places have been collected and analyzed in this research. Data obtained have been used to develop two quality systems. On the one hand, a classification of olive stone quality parameters has been developed and data are described in a similar way to standardized European quality label for wood pellets. On the other hand, a procedure to calculate a quality index has been designed. Both quality systems have obtained similar results. However, the first one has shown to be more strict. In conclusion, both of them could be used in order to provide a quality classification for olive stone residues. (C) 2013 Elsevier Ltd. All rights reserved.