In this study, Zn2+ substituted (into Ba position) barium hexaferrites with the chemical composition Ba1-xZnxFe12O19 (0.0 <= x <= 0.3) were produced by sol-gel approach. The Rietveld refinement of XRD powder patterns revealed both purity and the hexagonal structure of all products which have crystallite size within the range of 17-48 nm. The effect of Zn2+ ion substitution on the temperature-dependent and magnetic properties of Ba1-xZnxFe12O19 hexaferrites have been investigated in the temperature range 10-300 K and a magnetic field of +/- 50 kOe. Magnetization measurements revealed that all samples have hard ferromagnetic type magnetization and uniaxial anisotropy. As a result of Zn2+ substitution, the saturation magnetization gradually increases both at room temperature and at 10 K whereas coercivity decreases initially and then increases sharply reaching to a saturation at the highest zinc amount. On the other hand, as the temperature decreases both the saturation magnetization and the coercivity increase. The increase in the saturation magnetization was explained by weakened fluctuations of magnetic moments due to the low thermal energy and the increase in coercivity was due to the changing magnetic anisotropy with Zn substitution.