The present disclosure relates to an agent for dyeing and/or bleaching keratin fibers formed by: a first composition (A) comprising at least one basifying agent, and a second composition (B) comprising at least one oxidizing agent, wherein at least one of the two compositions (A) and (B) comprises at least one fatty substance not containing any carboxylic acid functional groups, the total amount of fatty substances in the mixture of compositions (A) and (B) representing at least 20% by weight relative to the total weight of the mixture of these compositions, and at least one of the compositions (A) and (B) comprises at least one sequestrant chosen from those of formula (I) and acids thereof:The present disclosure also relates to a process for dyeing and/or bleaching keratin fibers using the agent, and to a kit containing thereof.
