The dissolution, sorption and biodegradation of a chemical mixture were studied in batch tests, column tests and a pilot scale aquifer test. The chemical mixture included 1-butanol, 1,2,4-trimethylbenzene (TMB) and n-dodecane, two of which are the main components of gasoline. Sorption of 1-butanol and TMB on fine sand, and the co-solvency effect of 1-butanol on TMB sorption were investigated. Results exhibited a significant co-solvency effect of 1-butanol on TMB sorption. Column tests and the aquifer test were conducted to examine the dissolution and sorption properties of the mixture. Models CXTFIT and COMPSIM were used to simulate the column tests and the aquifer test, respectively. Both experimental and simulated results show that 1-butanol moves faster than TMB and n-dodecane due to its low sorption coefficient for the soil. TMB and 1-butanol readily biodegraded under aerobic conditions, but 1-butanol inhibited the biodegradation of TMB in the batch tests.