Alteration minerals dickite and kaolinite were detected in two hydrothermal Pb-Zn-Ag sulphide deposits in the northern Kosovo region. Dickite is associated with skarn mineralization in the Trepča (Stari Trg) deposit and kaolinite occurs in vein sulphide parageneses in the Crnac deposit. The mineralogical characteristics of dickite and kaolinite were determined by X-ray powder diffraction, Raman spectroscopy and scanning electron microscopy with EDS detector. Fluid-inclusion microthermometry and ion chromatography of leachates provided information on the P-T-X conditions of the genesis of dickite at Trepča. It was formed at temperatures between 290 and 330°C and pressures between 12 and 60 MPa from a fluid with salinity in the range 6–8.5 wt.% NaCl eq. and pH <5.5. Kaolinite was deposited from a fluid with minimum temperatures between 210 and 250°C, minimum pressure of 1.7 to 3.7 MPa, and salinity between 4.6 and 5.1 wt.% NaCl eq. Both dickite and kaolinite are related to the acidic pre-mineralization phase in the deposits.