A process for decreasing the flammability of textiles comprising a cellulosic fiber component and preferably a nitrogen-free thermoplastic fiber component which comprises treating the cellulosic fiber component with a condensate or a physical admixture of an allylurea and a phosphine/formaldehyde condensate such as a tetrakis (hydroxymethyl)-phosphonium salt to introduce allyl groups into the cellulosic component, and subsequently halogenating, preferably brominating, the allyl groups thus introduced.