The mitochondrion can be considered as the metabolic powerhouse of the cell, having a key impact on energy production, cell respiration and intrinsic cell death. Mitochondria are also the main source of endogenous reactive oxygen species, including free radicals (FR), which are physiologically involved in signalling pathways but may promote cell damage when unregulated or excessively formed in inappropriate locations. A variety of chronic pathologies have been associated with FR-induced mitochondrial dysfunctions, such as cancer, age-related neurodegenerative diseases, and metabolic syndrome. In recent years drug design based on specific mitochondria-targeted antioxidants has become a very attractive therapeutic strategy and, among target compounds, nitrones have received growing attention because of their specific affinity toward FR. Here, we describe protocols dealing with the preparation, mitochondria permeation assessment, electron paramagnetic resonance (EPR) spin trapping setting, and anti-apoptotic properties evaluation of a series of new linear nitrones vectorized by a triphenylphosphonium cation and labeled with a diethoxyphosphoryl moiety as 31P nuclear magnetic resonance (NMR) reporter with antioxidant property.