Turquoise hydrogen: an effective pathway to decarbonization and value added carbon materials, Volume 61 of the Series Advances in Chemical Engineering, reports the latest advances in turquoise hydrogen production technologies including thermo-catalytic, plasma and molten media conversion of natural gas and hydrocarbons streams. Turquoise hydrogen is emerging as a promising and feasible route to produce hydrogen from hydrocarbons, while directly capturing the carbon content in the form of highly valuable carbon materials (carbon black, carbon fibers and carbon nanotubes). Depending on the value of the produced carbon materials, which is strictly connected to their market demand and applications, such route is expected to enable hydrogen production at accessible costs (1-1.2 USD/kgH2). Compared to grey hydrogen from steam methane reforming processes where CO2 capture units significantly impact capital and operating costs, turquoise hydrogen production exploit an advantageous material-energy nexus. Indeed, splitting methane or hydrocarbon streams into their elements (H and C) 1) avoids the production of CO2, therefore limiting operating costs for clean-up, capture and storage, and 2) produces low weight carbon materials with properties that are similar or better than many products from the metal industry (aluminum, steel, etc.), ultimately reducing the carbon footprint of the energy intensive metal industry and the emissions from end-uses (e.g. decreased weight of aircrafts vehicles enabling improved fuel economy). As a further advantage, turquoise hydrogen represents a viable short-to-mid term solution compared to the more challenging energy system adaptation required by large-scale green hydrogen production. This volume covers a wide variety of aspects, from life cycle sustainability assessment, economic potential and applications of the wide spectra of carbon products, to more fundamental aspects of relevance for thermal pyrolysis reactor design such as catalytic and non-catalytic chemical kinetics, lab-scale experimental apparatuses, mass and heat transfer phenomena and related challenges, up to available industrial technologies. An overview of current trends in plasma and molten media pyrolysis reactors is also provided.