Sonochemical processes have been widely used in chemistry and chemical engineering field. Recently, these processes have found new applications in the environmental field, because of advantages in terms of operational simplicity, secondary pollutant formation and safety. Several studies have reported on sonochemical degradation of organic compounds that are toxic in nature. The objective of this review was to identify and examine some of the studies on sonochmical degradation of chlorinated organic compounds, phenolic compounds and organic dyes. This review also examines the basic theory of sonochemical reactions and the use of sonochemical reactors for environmental applications.