Abstract: Recent years have witnessed a series of milestone advancement in the synthesis of structurally authentic molecular actinide complexes in unusual oxidation states. Notable examples include the first synthesis and structural characterization of divalent thorium, uranium, neptunium and plutonium molecular complexes and the first single crystal structure of a tetravalent berkelium complex. It is urgent to summarize the recent advancement in this field and provide perspectives for its future direction. As the second part of this series of review, we will first briefly introduce the concept of “unusual oxidation states” of actinides and then focus on the synthesis and characterization of molecular actinide complexes in unusual oxidation states. In addition to provide a survey of literatures, we will discuss the remaining challenges of this field and its great impact on fundamental bonding theory of actinides and the nuclear science. At last, we will give perspectives for the future direction of this vibrant field.