g bothboron and chlorine in amounts equimolar to zirconium, respectively, and having the formula (HBO.sub.3) (ZrOH)Cl.multidot.xH.sub.2 O. It is also disclosed that the boratozirconium chloride forms an acidic viscous sol solution when being dissolved inwater, and the sol forms gels when being mixed with organic solvents such as methanol or ethanol.