Stability of organic solar cells (OPV) remains a big problem on the way to their commercialization. Different approaches are being investigated: development of intrinsically more photochemically stable materials, optimization of encapsulation, and implementation of getter and UV blocking layers. In this study, we investigate stabilization of OPV devices using hydroperoxide decomposers as stabilizing additives. A set of five commercially available additives of organophosphorus, organosulfur, Ni chelate, and blocked thiol type are compared, ternary blended into the active layer, under exposure to aging under ISOS-3 degradation conditions. Improvements in long-term performance of OPV devices were observed upon stabilization with Advapak NEO-1120, lifetime was prolonged by a factor of 1.7, and accumulated power generation increased by a factor of 1.4. The stabilizing mechanisms are discussed using spectroscopic and microscopic measurements.