Porous Carbon Nanoparticles (PCNs) with well-developed microporosity were obtained from bio-waste oil palm leaves (OPL) using single step pyrolysis in nitrogen atmosphere at 500–600 °C in tube-furnace without any catalysis support. The key approach was using silica (SiO₂) bodies of OPL as a template in the synthesis of microporous carbon nanoparticles with very small particle sizes of 35–85 nm and pore sizes between 1.9–2 nm.