Ozone addition is a promising method to enhance and control combustion and ignition processes. It can be produced efficiently at atmospheric or elevated pressure conditions and its lifetime is sufficiently long to allow for remote production and transport to reaction zones. Over the past decades, the effect of ozone addition on ignition and combustion processes has been extensively studied from bench top fundamental burners to practical internal combustion engines. Ozone has shown the capability to accelerate ignition and control ignition timing, enhance flame propagation, improve flame stabilization, pre-process fuel to modify emission and reactivity characteristics, and reduce certain pollutant formation. Such enhancement is closely related to ozone chemistry, especially the decomposition of ozone to produce atomic oxygen and the rapid exothermic ozonolysis reactions with unsaturated hydrocarbons. The former requires elevated temperature to release atomic oxygen and initiate fuel/atomic oxygen reactions typically in the preheat zone, while the latter initiates low temperature (even room temperature) direct fuel/ozone reactions. These findings provide new opportunities in the development of strategies to enhance and control combustion/ignition processes. This article provides a comprehensive review of the basic principles of ozone enhanced reactive processes, including fundamental ozone chemistry, ozone generation and quantification, and the progress in the study of ozone addition in combustion systems. (C) 2019 Elsevier Ltd. All rights reserved.