The bromate anion as a safe, cheap, stable and easily stored oxidizing system has been utilized for the oxidation of a wide range of alcohols and alkyl arenes to the corresponding aldehydes and ketones. The reaction was performed in the presence of guanidinium-based sulfonic acid as a Brønsted acid organocatalyst in aqueous acetonitrile at room temperature. Products are isolated in high yields and the catalyst could be easily recovered and recycled.