Electrical properties of CdTe single crystals, doped by Mn (1 × 1017–1 × 1019 at/cm3), were studied in the wide temperature range using high-temperature Hall effect measurements. To explain the obtained electrical properties the numerical simulation of the structure of both native and foreign point defect densities in the crystals was applied. Between the possibilities of whether predominantly Mn-single donors only or combined with Mn-containing associates occurrence in the crystals the second possibility was confirmed. High-temperature electrical measurements were explained in the framework of the Kröger's theory of quasi-chemical reactions between point defects in solids. It was done by investigating the series of differently Mn-doped CdTe single crystals. In the 1 × 1017–1 × 1019 at/cm3 Mn concentration range the measured free electron densities at high-temperature defect equilibrium were almost identical indicating clear donor activity of the dopant. •High-temperature electric measurements in CdTe single crystals.•Quasi-chemical approach and use of numeric simulation at treating these data.•Manganese solubility in CdTe limited to ~1 × 1017 at/cm3 at 873–1073 K.•Mn(Cd) in CdTe acting as donors with E(d) = 0.10 eV.•Existence in the crystals both individual Mn(Cd) donors and its associates with V(Cd).