Compressors consume 15% of energy in developed countries and contribute 3,000 megatons of CO₂ emissions annually. With rising demand for hydrogen and Compressed Air Energy Storage (CAES) systems, improving compressor efficiency is critical. Reciprocating compressors show potential for efficiency gains through coolant injection or spray cooling, but technical challenges remain. This paper reviews research on coolant injection in reciprocating compressors, examining efficiency improvements, coolant selection, injection profiles, and droplet behaviour. While most research has focused on discharge pressures of 2 to 7 bar for reciprocating compressors, with a maximum of 25 bar tested and simulated, high-pressure applications remain underexplored. Expanding studies to higher pressures is critical for advancing coolant injection in high-pressure compressors. The review examines simulation approaches, including one dimensional (1D) modelling and computational fluid dynamics (CFD), and their correlation with experimental results. The findings identify current limitations and provide insights to guide future advancements in high-efficiency, high-pressure compressor systems, addressing key challenges in energy-intensive applications.