Advances in nanoscale electronics require superior ceramic powders, preferable prepared with techniques for the direct synthesis of crystalline nanoparticles. Zinc ferrite (ZnFe2O4) nanopowders were prepared by co-precipitation method, from nitrate precursors. Crystalline powders having the single-phase cubic spinel structure were directly synthesized at temperature >= 80 degrees C in the presence of NaOH. The obtained powders are agglomerated with ultra-fine crystallites having the average crystallite size about 3-4 nm.