Acting as a neuromodulator, H₂S facilitates long-term potentiation and regulates intracellular calcium levels, which are important processes in learning and memory. Aberrant endogenous production and metabolism of H₂S are implicated in pathogenesis of neurodegenerative diseases including Alzheimer’s disease (AD) and Parkinson’s disease (PD). Various H₂S donors have shown beneficial therapeutic effects in neurodegenerative disease models by targeting hallmark pathological events (e.g., amyloid-β production in AD and neuroinflammation in PD). The results obtained from many in vivo studies clearly show that H₂S not only prevents neuronal and synaptic deterioration but also improves deficits in memory, cognition, and learning. The anti-inflammatory, antioxidant, and anti-apoptotic effects of H₂S underlie its neuroprotective properties.