An in-situ process for the grafting of a common poly(ionic liquid), poly(1-ethyl-3-vinylimidazolium bis(trifluoromethanesulfonyl)imide), from natural cotton was developed. Unexpectedly and only found for this special morphology, the PIL coating even at a weight fraction as low as 3.4 wt%, could run accelerated activation of cotton into porous carbons at temperatures above 600 degrees C under nitrogen. During the activation process, good preservation of the microscopic fiber structure and the macroscopic morphology was achieved, and the resulting microporous carbons are mechanically highly flexible. Due to the special activation reaction of the PIL coating with the cotton, the as-formed microporous carbon is highly temperature and oxidation-stable and can be used for electrocatalytic reactions, here exemplified by the oxygen reduction reaction. This work thus points out a new, very simple pathway to process biomass with special architecture into functional porous carbons for electrochemical energy conversion. (C) 2015 Elsevier Ltd. All rights reserved.