**Abstract**

Biomass is a renewable energy source to generate heat and electricity through the enhancement of various organic materials. Cistus slow pyrolysis of seeds and shells was carried out in a fixed bed reactor to determine the effect of pyrolysis temperature, heating rate, and particle size on the performance of pyrolysis. Therefore, pyrolysis experiments were performed at different temperatures, ranging from 300 to 500°C, with heating rates varying from 10 to 70°C.min<sup>1</sup> for shells and 7 to 28°C.min<sup>1</sup> for seeds. The particle sizes of samples range from 0.3 to 3.5 mm for shells and 0.075 to 1.2 mm for seeds. The highest yield of liquid products (53.31% for shells; 52.24% for seeds) was obtained at a pyrolysis temperature of 450°C and a heating rate of 40°C. min<sup>1</sup> for shells and 21°C.min<sup>1</sup> for seeds. The functional groups and chemical compounds present in the bio-oil obtained under optimal conditions were identified by FTIR. The calorific value of the bio-oil was equal to 37.05 and 37.93 MJ.kg<sup>1</sup> for shells and seeds, respectively. The obtained results show that the bio-oil from the pyrolysis of Cistus shells and seeds could be used as a renewable fuel or a source of pharmaceutical and chemical raw material.

**Keywords:** bio-oil, bio-fuels, renewable energy, fixed bed pyrolysis, seeds of *Cistus Ladaniferus*, rockrose, green energy, viscosity
