The present disclosure relates to multi-component packaging units (kits-of-parts), ready-to-use agents, and methods for reductive decolourisation of dyed keratinous fibres. In one example, the multi-component packaging unit (kit-of-parts) for reductive decolourisation of dyed keratinous fibres includes,(I) a first container (A) including a cosmetic agent (a) and(II) a second container (B) including a cosmetic agent (b),whereinthe first container (A) and the second container (B) are provided separately from one another,the cosmetic agent (a) in the first container (A) includes(a1) one or more reducing agent(s) that is/are solid at room temperature, and(a2) one or more oxidant(s) that is/are solid at room temperature, and wherein the cosmetic agent (b) in the second container (B) comprises (b1) one or more alkalising agent(s).
