The extractant, methylimino-bis-N,N'-dioctylacetamide (MIDOA), was used for the extraction of soft acid metals. It was found that MIDOA can extract not only Cr(VI), Mo(VI), W(VI), Tc(VII) and Re(VII), whose metals can form oxonium anions due to their high oxidation states, but also other metal cations, like MIDOA were also studied and discussed in this paper.