Pyrolysis of acid pretreated peanut (Arachis hypogaea) shells was examined in order to improve the yield of liquids (bio-oils) and the characteristics of the three kinds of pyrolysis products. Also, pyrolysis of the pristine shells was comparatively investigated. The acid pretreatment was carried out employing a dilute HCl solution and it successfully diminished the ash content of the shells. Pyrolysis assays were performed in a fixed-bed reactor at different process temperatures (400 degrees C, 500 degrees C, and 600 degrees C). The maximum bio-oil yield was obtained at a temperature of 500 degrees C for both the pretreated and the pristine shells, but pyrolysis of the formers yielded more bio-oils than the untreated ones (42 wt% vs. 33 wt%). The increase of the process temperature resulted in a reduction of the solid (bio-char) generation for both samples. Demineralization also led to a further reduction of the bio-char yield. Regarding the products characteristics, neither the pretreatment nor the temperature had a noticeable influence on the elemental composition of the bio-oils. However, water content of the bio-oils was lower for the ones arising from pyrolysis of the demineralized shells although it increased with growing process temperature. Likewise, pyrolysis of the demineralized shells resulted in bio-chars with less ash, improving their potentialities as bio-fuels. Also, the bio-chars arising from the treated shells at the higher temperatures (500 degrees C and 600 degrees C) resulted in higher BET surface areas (up to 300 m(2)/g), pointing to their possible use as rough adsorbents or for further upgrading to activated carbons. (C) 2017 Elsevier Ltd. All rights reserved.