The structural properties of Tc-Zr binary alloys were investigated using combined experimental and computational approaches. The Tc2Zr and Tc6Zr samples were characterized by X-ray diffraction analysis, scanning electron microscopy, electron probe microanalysis, and transmission electron microscopy. Our XRD results show that Tc6Zr crystallizes in the cubic alpha-Mn-type structure (/(43) over barm space group) with a variable stoichiometry of Tc6.25-xZr (0 < x < 1.45), and Tc2Zr has a hexagonal crystal lattice with a MgZn2-type structure (P6(3)/mmc space group). Rietveld analysis of the powder XRD patterns and density functional calculations of the "Tc6Zr" phase show a linear increase of the lattice parameter when moving from Tc6.25Zr to Tc4..80Zr compositions, similar to previous observations in the Re-Zr system. This variation of the composition of "Tc6Zr" is explained by the substitution of Zr for Tc atoms in the 2a site of the alpha-Mn-type structure. These results suggest that the width of the "Tc(6)Ze" phase needs to be included when constructing the Tc-Zr phase diagram. The bonding character and stability of the various Tc-Zr phases were also investigated from first principles. Calculations indicate that valence and conduction bands near the Fermi level are dominated by electrons occupying the 4d orbital. In particular, the highest-lying molecular orbitals of the valence band of Tc2Zr are composed of d-d sigma bonds, oriented along the normal axis of the (110) plane and linking the Zr network to the Tc framework. Strong d-d bonds stabilizing the Tc framework in the hexagonal unit cell are also in the valence band. In the cubic structures of Tc-Zr phases, only Tc 4d orbitals are found to significantly contribute near the Fermi level.