In a current artificial synthetic pathway in Escherichia coli (E. coli), styrene oxide is the starting material and acyloins, which can be used for pharmaceuticals are the end products. If the pathway could be extended to start with styrene, it would be economically beneficial to use this biochemical synthesis pathway. The aim of this project was thus to find an enzyme (monooxygenase, MO) that can catalyze the reaction of styrene into styrene oxide. Bibliographical search after monooxygenases resulted in two enzymes from Mycobacterium strains (ETN and PMO), one enzyme from Nocardia corallina B-276 (AMO) and enzymes from Pseudomonas and Rhodococcus strains (SMOs). The SMOs from Pseudomonas consist of the two components StyA and StyB, of which StyA converts styrene into (S)-styrene oxide with the help of FADH2. StyB reduces the FAD back into FADH2 so that the reaction can continue. Since FAD reductases already exist naturally in E. coli, only the StyA part was chosen in this project. During expression of StyA, it was observed that putative radicals were formed. When a standard procedure to purify the enzyme was followed, it was observed that the enzyme had formed inclusion bodies, leading to unsuccessful purification. Thus, measurements on activity could not be performed. The experiences from this project can be used as a guide for further experiments with StyA, where attempts to optimize the procedures are suggested.