As a result of the interaction of triphenylbismuth and vinylacetic acid with tert-butyl hydroperoxide at ambient temperature in ether, a new compound triphenylbismuth bis(but-3-enoate) Ph3Bi(O2CCH2CH=CH2)2 was obtained with the 60% yield, and the melting point of 131 °C. In the IR spectrum of the substance recorded in the KBr pellet on an “IR Prestige-21” set, Shimadzu, Japan, in the range of 4000–400 cm–1, the signals of valence vibration (v, cm–1) were found to equal 3054 (Ph-H), 2978 (CH2), 1600 (C=C), 1599 (COO-as); 1471, 1439, 1362 (COO-s), 919, 734, 680; 573 (Bi-C), 454 (Bi-O). In the 1H NMR spectrum taken in deuterochloroform on an Agilent DD2 400 spectrometer, the following signals were detected: 8.15 (dd, J = 8.3, 1.0 Hz, 6H), 7.59 (t, J = 7.6 Hz, 6H), 7.46 (dd, J = 11.0, 3.7 Hz, 3H), 5.76 (td, J = 17.1, 6.9 Hz, 2H), 4.96–4.86 (m, 4H), 2.86 (dt, J = 6.9, 1.3 Hz, 4H). 13C NMR: 40.44 (2C, -CH2-), 116.70 (2C, CH2=), 130.71 (3C, Ph), 131.13 (6C, Ph), 132.34 (6C, Ph), 133.90 (2C, =CH-), 160.38 (3C, Bi-C), 177.43 (2C, C=O). The molecular structure of the compound was found by X-ray diffraction. X-ray diffraction was performed on an Oxford Diffraction Gemini Sapphire3 diffractometer using Mo Ka radiation (λ = 0.71073 Å, graphite monochromator) at T = 293 K. P21/s, a = 12.7672(3), b = 22.0170(4), c = 8.9767(17) Å, β = 104.831(2)º, V = 2439.25(9) Å3, Z = 4. The bismuth atom in the structure has a distorted trigonal-bipyramidal coordination. The O-Bi-O axial angle is 171.5 (2)°. The Bi–O and Bi-C bond lengths are 2.280(4)–2.310(3) and 2.197(7)–2.209(6) Å.