The present paper deals with the effect of hydrous oxides on zero point of charge (ZPC) of red soils, kaolinites and synthetic amorphous aluminosilicates, and the distinction of hydrous oxide-type surfaces in soils. The results show that hydrous oxide-type surfaces could be divided into two subgroups which have completely different characteristics. In the samples of the soils and clays studied, the iron oxide (Fe-OH) and aluminium oxide (Al-OH) surfaces with s high ZPC were pH-dependent positive charge sub-surface, which tended to increase the ZPC of the samples, and silica (Si-OH) surface with a low ZPC was pH-dependent negative charge sub-surface, which tended to decrease the ZPC of the samples. The ZPC of synthetic amorphous sluminosilicates were significantly positively correlated to the Al₂O₃/SiO₂ molar ratio of the satnpies.