The discovery of lytic polysaccharide monooxygenases (LPMOs) as a cellulase component has brought a significant revolution to the enzymatic degradation of lignocellulosic biomass. LPMOs are powerful oxidative enzymes which can cleave glycosidic bonds in polysaccharides, such as starch, cellulose, xylan and chitin. The mechanism of action and analysis of LPMOs is complex due to which its discovery has been delayed even though its other counterparts as cellulase components have been known for some time. Their significance in biomass hydrolysis is presented in this chapter along with details of the mechanism of action and determination methods associated with complexities and future avenues. The addition of LPMOs can further reduce cellulase cost in enzyme cocktails of enzyme manufacturers, which has increased the rate of hydrolysis by more than twofold.