ZnO crystals homogeneously doped with transition metals and rare-earth elements during the growth process are promising light-emitting materials. The nanoporous matrices on highly conductive ZnO substrates, filled with nanowires and nanotubes of various materials, are promising structures for optoelectronics and photonics. The chemical vapor transport (CVT) in sealed ampoules remains one of the cheapest and simplest methods of obtaining crystals with controllable electrical parameters and impurity composition. The polycrystalline unseeded growth is observed when C and CO are used as a transport agent (TA). ZnO crystals obtained using H2 are usually characterized by angle boundary defects and voids. HCl offer the possibility to grow more qualitative crystals, but this TA is limited by a very low growth rate of crystals that is caused by the low temperature dependence of the pressures of the main CVT gaseous species.  The simultaneous use of HCl and other TAs (H2, CO or C), causing a higher temperature dependence of the pressures of the chemical interaction species, is promising for the increase in growth rate of ZnO. Present investigation is devoted to obtaining ZnO crystals using complex transport agents. The thermodynamic analysis for composition of ZnO+HCl, ZnO+HCl+H2, ZnO+HCl+CO and ZnO+HCl+C CVT systems is carried out for wide temperature range and for various loaded TA pressures. The influence of the growth temperature and of the density/composition of TA on the growth rate is investigated theoretically and experimentally. The increase of the growth rate of up to 1.5 mm per day has been achieved. The TA compositions favorable for the growth of non-polar, semi-polar and polar planes of a hexagonal structure are found. Unseeded growth of the high crystalline quality single crystals with an etch pit density ~ 103 cm^-2, controllable growth direction, and controllable stoichiometric deviation is demonstrated (Fig. 1(a)). High transparency in a visible spectral range and effective edge luminescence are observed (Fig. 1(b)). The variation of the main electrical parameters of crystals by changing the Cl doping level is demonstrated (Fig. 1(c)). The advantages and disadvantages of various TAs based on HCl are summarized.