The phenomenon of quasi-steady ablation is investigated theoretically for a semi-infinite charring material. The one-dimensional ablation is assumed to proceed under the influence of a steady external heat source. The steady temperature distributions in the virgin and char zones are derived and the associated steady ablation rate is also obtained theoretically. Though the results presented in this study are obtained for the case of steady ablation, they are useful for the verification of transient numerical models of charring ablator, especially those based on a fixed coordinate system. (c) 2006 Published by Elsevier Ltd.