Metal nitrides/oxynitrides-based materials inherently possess band gap lower than the corresponding oxide counterparts and therefore is a potential class of compounds that offer visible light active photocatalysts. Nitride-based semiconductors have gained immense attention for H2 generation applications as photocatalysts or cocatalysts owing to their appropriate band gap and alignment, simple, fast synthetic methods at lower costs, better stability: chemical and thermal, and also low level of toxicity. Present chapter focusses on the key features of nitride/oxynitrides as photocatalysts for solar energy conversion. The physical and chemical routes for synthesis of nitrides and oxynitrides, along with their efficiency for water splitting reaction is discussed. The band gap engineering, underlying principles and processes involved in photocatalytic H2 generation over different classes of nitrides such as transition metal nitrides, Group III nitrides, oxynitrides and perovskites are reviewed.