The history of mineral flotation is a record of over a century of impressive innovations, especially in the development of flotation chemistry and chemicals, the principles of their action, their manufacture and the role they play in sustaining efficiencies and productivities even as the quality and grade of ores decline, and the severity of the challenges increases. We emphasize the major innovations that have directed progress on this subject, especially those innovations that have positively impacted industrial scale applications. An analysis is given that organizes the evolution of flotation chemistry and reagents into four historical and one emerging period. As in many other technology areas, flotation chemistry research and development have reached a plateau in the face of mounting industry challenges related to water and energy consumption, decline in the ore quality, economic uncertainty, and health, safety and environmental (HSE) aspects. Elevating us off this plateau will require several necessary steps, including more detailed, holistic understanding of practical systems, better integration of chemical effects into flotation models, a more robust education system to produce adequate numbers of qualified engineers, development of novel technologies and chemical schemes that address the challenges identified above, and a stronger commitment by mining companies to actually adopt those innovations. Success in developing novel technologies will be greatly improved when we can confront the chemical complexity in flotation systems. This in itself is one of the grand challenges in the emerging period. We outline some directions to achieve this goal. The mineral processing industry must take the initiative towards these goals in order to bring about the necessary transformation if we are to maintain a sustainable technology. (C) 2016 Elsevier Ltd. All rights reserved.