Cytochrome P450 peroxygenases are a niche subclass of heme enzymes that can functionalise C-H bonds in fatty acids using hydrogen peroxide (H2O2). Recently, it has been demonstrated that the more abundant cytochrome P450 monooxygenase enzymes, can be modified to function as peroxygenases through protein engineering. This would enable the selective oxidation of substrates without the addition of expensive cofactors or electron transfer partner proteins. However, too much H2O2 can inactivate these protein enzymes by reacting with the heme centre. Protein crystallographic studies on these peroxygenase P450s have been performed, whereby the addition of H2O2 to a substrate-bound crystallised enzyme have allowed for an in crystallo reaction to occur. The development of methods of in situ H2O2 formation in the presence of both natural and engineered P450 peroxygenases, to increase the efficiency of H2O2-driven catalytic activity will be described. This includes the use of light-activated flavin systems and chemical oxygen surrogates that supply H2O2. Preliminary studies on the addition of tags to these peroxygenases to allow their immobilisation onto solid surfaces, such as silica, for applications in flow chemistry will be presented. Ultimately, the goal is to be able to apply these different approaches for larger scale oxidative reactions.