Solid solutions Re1-xMnxO2 (x=0 008 0 21) with a tetragonal rutile-type structure (sp gr P4(2)/mnm z=2) have been synthesized from NH4ReO4 KReO4 and KMnO4 in argon atmosphere at 450-520 C in a quartz cell According to XPS measurements Mn in solid solutions Re1-xMnxO2 is present as Mn3+ and Mn2+ cations while the degree of oxidation of Re partly increases to penta- or hexavalent state A transition of ReO2 presumably in the antiferromagnetic state at 41K was for the first time established by magnetic measurements Along with the anomaly at 41K the second magnetic transitions at 6 5K (x = 0 08) and 11 K (x = 0 21) was registered in these solid solutions (c) 2010 Elsevier B V All rights reserved