This paper provides an extensive analysis of the literature on technological, economic, and environmental aspects for clean-hydrogen production. Hydrogen production routes that are compatible with renewable and nuclear sources are introduced, highlighting the recent advances and developments found in the literature on this topic. Discussions on recent and future expectations on cost aspects of clean-hydrogen economy are introduced in generic cost-based comparisons. In addition, recent literature on environmental aspects of common clean-hydrogen production technologies is investigated and their results are analyzed. Among clean energy sources, lower electricity prices from nuclear and geothermal energy make these sources feasible for low-cost hydrogen generation that has the potential to compete with fossil-based hydrogen production. Solar and wind conversion technologies and their intermittent nature are strongly affecting hydrogen production cost. However, mature technologies provide competitive hydrogen cost values, especially when integrated to electrolysis-based technologies. Ongoing research shows promotive and encouraging results for a clean and carbon-free energization of hydrogen production in the near future. (C) 2019 Elsevier Ltd. All rights reserved.