PURPOSE: To provide a soluble tellurium composition useful especially for coating tellurium on a metal surface, which is prepared by adding a cyclodextrin to the aqueous system containing tellurium. In this composition, tellurium ions can be solubilized in a mid pH range.
CONSTITUTION: The soluble tellurium composition, wherein tellurium ions are solubilized even in the pH range of 2.5-11 at which tellurium ions are generally insoluble, comprises (A) water, (B) at least 0.00001 wt.%, preferably 0.00001-1 wt.%, based on A, of tellurium or tellurium ions (tellurium oxide or tellurate is preferred as an ion source), and (C) an effective amount, which is able to solubilize and/or stabilize B, of a cyclodextrin (preferably β-cyclodextrin) (wherein, the molar ratio of the cyclodextrin to the tellurium ions is at least 10:1). The composition is prepared by adding a tellurium ion source into water which has been adjusted its pH to a pH at which tellurium ions are soluble, the adding an effective amount of cyclodextrin to the tellurium ion-solubilized solution thus obtained, and adjusting the pH of the solution to 2.5-11.