This study seeks to determine the antioxidant and neuroprotective properties of aqueous extract of ripe and unripe Capsicum pubescens (tree pepper) on some pro-oxidant induced lipid peroxidation in rat’s brain (in vitro). The total phenol, vitamin C, ferric reducing antioxidant property (FRAP) and Fe (II) chelating ability of the extracts of C. pubescens were determined. Thereafter, the ability of the extracts to inhibit lipid peroxidation (induced by FeSO4, sodium nitroprusside or quinolinic acid) in rat’s brain homogenates (in vitro) was determined. The results of the study revealed that ripe C. pubescens had a significantly higher (P < 0.05) total phenol content [ripe (113.7 mg/100 g), unripe (70.5 mg/100 g)] and reducing power than the unripe pepper. However, there was no significant difference (P > 0.05) in the vitamin C [ripe (231.5 μg/g), unripe (224.4 μg/g)] content and Fe (II) chelating ability of the extracts. However, both extracts significantly (P < 0.05) inhibited lipid peroxidation induced by the pro-oxidant agents [25 μM Fe(II), 7 μM sodium nitroprusside and 1 mM quinolinic acid] in the rat’s brain homogenates in a dose-dependent manner. Nevertheless, the ripe pepper extracts inhibited MDA (Malondialdehyhide) production in the rat’s brain homogenates than the unripe pepper. Conversely, both extracts did not significantly (P > 0.05) inhibit Fe (II)/H2O2 induced decomposition of deoxyribose. It was therefore concluded that ripe and unripe C. pubescens would inhibit lipid peroxidation in rat brain in vitro. However, the ripe pepper was a more potent inhibitor of lipid peroxidation in the rat’s brain; this is probably due to its higher phenol content and reducing power.