In solid fuel conversion systems, the release of alkali species can cause severe problems such as fouling, slagging, corrosion, and erosion. Especially in future coal-fired combined cycle processes such as pressurized pulverized coal combustion (PPCC), alkali species can cause corrosion of the gas turbine blading. In order to solve these problems, detailed information about the alkali release is required. In this work, the influence of coal composition and operating conditions on the release of alkali species is investigated. For this reason, laboratory combustion experiments with six different hard coals were conducted at temperatures of 800 and 1200 degrees C and absolute pressures of 1, 3, and 9 bar. High pressure mass spectrometry (HPMS) was used for online analysis of combustion products such as HCl, NaCl, KCl, SO2, and Na2SO4. In addition, two of the coals were subjected to a leaching procedure. Themodynamic equilibrium calculations with the software package FactSage 5.4 and the FACT database were conducted for comparison with the experimental findings.