PURPOSE: To prepare a homogeneous and stable tellurium-contg. soln. having long-term stability and suitable for use as a starting material for manufacturing a catalyst by using a specified reaction accelerator when tellurium dioxide is reacted with hydrogen peroxide.

CONSTITUTION: Tellurium dioxide powder is suspended in pure water, and a reaction accelerator selected from the oxides, oxyacids and oxyacid salts of molybdenum and tungsten such as ammonium paramolybdate is dissolved in the suspension. To suspension is heated, and an aqueous hydrogen peroxide soln. is added to cause a reaction. By this method the soln. velocity of tellurium dioxide is increased, the self-decomposition of hydrogen peroxide is inhibited, and a homogeneous and stable soln. contg. tellurium is obtd. By combining the reaction accelerator with an auxiliary such as ammonium ion, the soln. velocity is further increased.