Abstract This paper reports the synthesis and characterization of an organic silsesquioxane (SQ) containing Sivinyl and SiH groups named as vinylhydridosilsesquioxane (SQVH‐12). Detailed investigation of the structure of this organosilsesquioxane revealed that SQVH‐12 has a highly cross‐linked (polycyclic) SiO network of silsesquioxane with Sivinyl and SiH functional groups. Thermogravimetric analysis of the pyrolysis behavior of SQVH‐12 yielded a high percentage of ceramic residue (~92%) at 1200°C under an argon atmosphere. The presence of functional groups in SQVH‐12 and the high rate of ceramic residue highlights the potential usefulness of SQVH‐12 as a filler for vinyl‐containing polysiloxanes. Thus, further research of SQVH‐12 can find applications in a wide variety of areas such as additive manufacturing, protective coatings, and advanced composites.