Zeolite ZSM-5 was synthesized successfully, in situ, on pyrokaolin microspheres (PKM) under hydrothermal conditions, without the use of an organic amine template. The utility of alkali-modified pyrokaolin microspheres (AMKM) was also evaluated. The resulting products were characterized using X-ray diffraction, scanning electron microscopy (SEM) and N2-adsorption isotherm data. The material containing ZSM-5 synthesized from the system PKM-additional silica-water had a large surface area and pore volume with significant enhancements in the micropore surface area and micropore volume. The SEM images show that the synthesis of zeolite ZSM-5 from pyrokaolin microspheres (PKM) led to the formation of polycrystalline aggregates <2 μm in size. The purity of the zeolite ZSM-5 produced was affected by both the pH value of the reactant system and the reaction temperature. In the system containing AMKM-additional silica-water, very little of the synthesized zeolite resided on the kaolin microspheres.