ThPt3+xBe (x = 0.08) is synthesized by arc melting of a mixture of the elements. It crystallizes with its own type of structure [space group I4/mmm (No. 139), a = 7.7370(4), c = 11.4990(6) Å], which can be related to the cubic Ru3Sn7 and W2Cr21C6 types. Measurements of magnetic susceptibility, electrical resistivity and specific heat indicate ThPt3+xBe (x = 0.08) to be a diamagnet [χ0 = –9.0(3) × 10–6 emu mol–1] with metallic electrical resistivity, in good agreement with the calculated electronic structure [N(EF) = 3.2 states eV–1 f.u.–1]. A chemical bonding analysis was performed by the QTAIM and ELI‐D approaches.