He made a significant contribution to the discovery and characterization of photocatalytic properties of titanium dioxide (TiO2), for which he shared the 2004 Japan Prize with his former student Akira Fujishima.

[1] In 1949 Honda received his bachelor's degree in engineering from the University of Tokyo.

He then spent several years in France, where he defended a PhD in 1957 at the University of Paris.

After returning to Japan he obtained a second doctorate degree, from the University of Tokyo in 1961.

[1] In the late 1960s Honda and his doctorate student Akira Fujishima discovered the Honda-Fujishima effect - photocatalytic water decomposition (photolysis) upon exposing a titanium dioxide electrode to strong light.