This thesis presents the conceptual design and comparison of five versions of regional freighter aircraft based on the ATR 72. The versions comprise four baseline designs differing in their propulsion systems (jet/turboprop) and the fuel they use (kerosene/hydrogen). The fifth version is an improved further development of the hydrogen-fueled turboprop aircraft. For aircraft modeling the aircraft design software PrADO is applied. The criteria for the overall assessment of the individual aircraft versions are energy use, climate impact in terms of global warming potential (GWP) and direct operating costs (DOC). The results indicate that, from an aircraft design perspective, hydrogen is feasible as fuel for regional freighter aircraft and environmentally promising: The hydrogen versions consume less energy to perform a reference mission of 926 km (500 NM) with a payload of 8.1 t of cargo. The climate impact caused by the emissions of hydrogen-fueled regional freighter aircraft is less than 1 % of that of kerosene-fueled aircraft. Given the circumstance that sustainably produced hydrogen can be purchased at a price that is equivalent to kerosene with respect to energy content, hydrogen-fueled regional freighter aircraft are also economically competitive to current kerosene-fueled freighters. In consequence, regional freighters appear especially favorable as first demonstrators of hydrogen as aviation fuel, and cargo airlines and logistics companies may act as technology drivers for more sustainable air traffic. The potential of regional freighter aircraft alone to mitigate climate change is marginal. The share of national and regional air cargo traffic in global manmade climate impact lies in the region of 0.016 % to 0.064 %, which also represents the maximum reduction potential. The presented work was to a large extend performed during the joint research project "The Green Freighter" under the lead of Hamburg University of Applied Sciences (HAW Hamburg).