The present application relates to a colouring solid particle for dyeing keratin fibres, in particular human keratin fibres such as the hair, comprising a core containing one or more direct dyes and/or one or more oxidation dye precursors and an upper coating layer covering said core and containing one or more cellulose ethers. The present application also relates to a process for preparing a dye composition comprising one or more colouring solid particles, to a process for the oxidation dyeing of keratin fibres, comprising the application of the composition obtained to said fibres, and to the use of this composition for dyeing keratin fibres.