Ethiopia is one of the African countries with biomass and charcoal is used as a solid fuel for cooking, which was produced traditionally. The production of char in the traditional earth method had a significant impact on the yield, quality of charcoal and environmental pollution. Thus, the traditional method of charcoal production was improved using one of the thermochemical technologies called pyrolysis. In this study, the fixed slow pyrolysis reactor was manufactured with an annual production capacity of 16.7 tones char. The size of the reactor volume, inside diameter, height, and critical insulation radius was calculated as 0.085 m3, 42 cm, 70 cm, and 3 mm respectively. The proximate analysis (MC, VM, ASH, and FC) for raw eucalyptus was obtained as 8.5%, 63%, 1.2%, and 27.2% respectively and for charcoal product was obtained as 3.5%, 32.8%, 1%, and 62.7% respectively. The optimum residence time for the better yield of charcoal for 3 years aged eucalyptus feedstock was 188.88 minutes and the maximum char yield was obtained 32.39%, the maximum selectivity was achieved at a residence time of 161.69 minutes, which was 72.02% , and its conversion was increased with residence time. The burning rate, water boiling time to boil 2 liters of water and time taken to burn to ash completely for the char produced from slow pyrolysis reactor was ranged from 1.6 ± 0.014 g/min, 30 ± 0.6 minutes and 310 ± 2.5 min respectively and for the char produced from traditional earth-kiln method was 1.6 ± 0.038 g/min, 50 ±0.57 minutes and 305 ± 3.0 min respectively. From the proximate analysis the average HHV of raw eucalyptus was found to be 19.5 MJ/kg and the average HHV of charcoal was found to be 27.3 MJ/kg with an absolute error of 2.1% and 2.7% respectively. A shell and tube heat exchanger was added and (bio-oil +water) was recovered from the condensable vapors, which are removed to the environment and the yield of (bio-oil +water) was increased with residence time. The CO and PM emission was low for char produced from pyrolysis than traditional methods and the CO and PM emission was low during slow pyrolysis charcoal production than during traditional earth-kiln production methods. The surface temperature distribution increased with reactor height from the bottom to the upper part of the slow pyrolysis reactor, which showed there was a good heat transfer.