Sources of clean energy are becoming increasingly common, and the use of solar thermal energy has also been rising. This paper presents a solar air heater designed with a vegetable material as insulating material, date palm wood, widespread in tropical and saharan countries for use in drying. The study focuses on the comparative thermal performance of this collector and another collectors identical in design, fabrication, and operating under the same conditions, using glass wool as heat insulation. The thermal efficiencies of differents insulators collectors were performed: a) insulator with Petiole Piece, b) insulator with Fibers Piece, c) insulator with Petiole powder, d) insulator with Fibers powder, e) insulator with Petiole + gypsum, f) insulator with Fibers + gypsum insulation and collector with glass wool insulation were evaluated and graphs were plotted. The final results showed that thermal efficiencies of date palm wood (Petiole + gypsum) insulated collector was 37.7% higher than glass wool insulated collector. The average outlet air temperature of glass wool insulated was 7% lower than Petiole + gypsum insulated collector. Hence the date palm wood is a good candidate for the development of efficient and safe insulating materials. Crown Copyright (C) 2018 Published by Elsevier Ltd. All rights reserved.