Abstract: A topological semimetal PtSn4 single crystal is grown and the following properties are studied: its electrical resistivity in the temperature range from 4.2 to 300 K, galvanomagnetic properties at temperatures from 4.2 to 80 K and in magnetic fields of up to 100 kOe, and optical properties at room temperature. Theoretical calculations of the electronic structure are performed. It is shown that the residual resistivity is rather small: ρ0 = 0.47 μΩ cm, which is characteristic of a “good” metal. The ρ(T) dependence is of the metallic type, increasing monotonically with temperature. Analysis of the temperature dependences of the magnetoresistivity suggests that the Fermi surface of the PtSn4 compound may contain closed sheets. Studies of the Hall effect and the estimates made in the single-band model allowed us to conclude that the predominant type of current carriers are holes with concentration n = 6.8 × 1021 cm–3 and mobility μ ≈ 1950 cm2/(V s) at T = 4.2 K. It is shown that the optical properties of PtSn4 have features characteristic of “bad” metals. The calculation of the electronic structure of PtSn4 showed that, in general, this compound has a structure characteristic of metallic systems with a sufficiently large number of electronic states at the Fermi level, which is consistent with the experimental results on the electronic transport and optical properties of the PtSn4 single crystal.