Drop Tube Furnace (DTF) tests are usually carried out at temperatures higher than 1000 °C, and effects of lower temperatures are not well-documented. Hence, medium range temperatures (600-900 °C) in a "Drop Tube Furnace" (DTF) were investigated to determine whether they are really ineffective to alter the fuel structure. For this purpose, whole shells of hazelnut and its size fraction of 0.5-1 mm were subjected to oxidative conditions in a DTF at temperatures between 600-900 °C. Then, the particles rescued after this thermal process were examined using Thermogravimetric Analysis (TGA) and other standard test methods such as proximate analysis, calorific value and elemental analysis, as well as other techniques including BET surface area, Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscopy (SEM). It was concluded that despite some properties are not almost changed, remarkable variations also are in question, and this confirms the fact that even low temperatures in DTF are not totally ineffective when the material is such a high reactive biomass species. Thus, it is likely to suggest that processing in DTF is a technique not only for simulation of thermal processes but also for rapid pretreatment of biomass to improve its intrinsic characteristics at medium range temperatures. © 2012 Elsevier Ltd. All rights reserved.