To provide an anhydrous paste for decoloration which is stable to temperature change and thermal shock, and has a homogenous and strong decolorizing effect.

This anhydrous paste for decolorizing human keratin fibers such as hair containing at least a peroxygenated salt and at least an alkali agent, contains 15-35 wt.% of a polydecene of the formula C10nH[(20n)+2]; (n) is 3-9, preferably 3-7 and 0.01-10 wt.% of at least a gelling agent selected from a di-block, a tri-block, a multi-block or a radial block polymer comprising a segment of a styrene type monomer and a segment of a thermoplastic monomer, a hydrophilic or lipophilic fumed silica.