Anthropogenic input of organic compounds into aqueous environments and the effects of these contaminants on ecosystems, as well as human health are of great concern. Many contaminants are found in concentrations in excess of the accepted daily intake (ADI) values. The fate of these contaminants as they degrade by chemical processes, specifically via reactions with hydroxyl radicals (·OH), and the rate of that degradation, is of interest. Hydroxyl radicals are a major contributor to the breakdown of many contaminants in natural systems. The present study focused on measuring the product distributions from the reactions of selected substrates with ·OH, and the determination of rates of reactions relative to benzene (PhH). From the data collected, models for predicting degradation pathways and rates of larger, more complex molecules can be developed. In this study ·OH was generated by thermolysis, and reacted with two competing substrates. The products of the reaction were trapped with TEMPO, a nitroxyl radical, then derivatized to allow for analysis and characterization by GC/MS. The ratios of ·OH addition products yield relative rate coefficients that may be subjected to Arrhenius analysis to probe the effect of structure on reactivity.