Hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs) are two classes of compounds which are being used as CFC replacement. HCFCs and HFCs contains one or more C-H bonds which can be attacked by OH radicals in the lower atmosphere. The atmospheric transformation products of HCFCs and HFCs are dictated by the relative importance of reactions such as (3-6). To understand the atmospheric chemistry of HCFCs and HFCs, it is necessary to study the chemistry associated with the halogenated peroxy radicals. In this paper, results obtained from recent studies of halogenated peroxy periodicals over the past 3-4 years are reviewed. For a series of halogenated peroxyradicals, their UV spectra, the kinetics of their reaction with NO, the kinetics of their reaction with NO2, and the products observed following their self reaction are studied.