This work deals with the use of chemically modified wheat straw as efficient low-cost adsorbent for combating oil-spills in aquatic environment. The autohydrolyzed wheat straw was produced from the corresponding raw material by autohydrolysis in a PARR batch reactor (autoclave) at 160-240 degrees C for 0-50 min isothermal reaction time (following a non-isothermal preheating period). Oil adsorbency tests were performed, using diesel and crude oil spills in freshwater and seawater. Diesel and crude oil adsorbency values were found to increase up to a maximum by intensifying the autohydrolysis conditions, i.e., time and temperature. The adsorbency values were estimated by a proposed novel model incorporating the autohydrolysis severity factor R-0. Optimal modification conditions were found for log R-0 =5.15 (i.e., 200 degrees C, 10 min isothermal time period) giving diesel adsorbency up to 6.65 g g(-1) and crude oil adsorbency up to 6.91 g g(-1). The maximum adsorbency values were comparable to those of the commonly used commercial adsorbents. (C) 2013 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.