For the first time, practically single-phase MAX-phase solid solutions with the general formula (Ti1–xTax)3SiC2, where «x» ranges from 0 to 0.17, were synthesized by high-temperature pressureless vacuum sintering at temperatures between 1400°C and 1600°C. The lattice parameters of hexagonal (Ti1–xTax)3SiC2 were determined by X-ray diffraction using Rietveld refinement. This analysis showed anisotropic lattice broadening upon the introduction of Ta into Ti3SiC2. This observation is consistent with density functional theory (DFT) calculations; the deviation between the measured and calculated lattice parameters was less than 1%. The microstructure of the materials consists of a porous three-dimensional (Ti1–xTax)3SiC2 matrix with inclusions of tantalum-titanium silicide. The electronic structure of the obtained compounds was analyzed using the density functional theory method. The replacement of Ti atoms by Ta does not cause significant changes to the system.