The molecular complexes of the potassium atoms with methanol and 1,2-ethanediol were generated in a flow reactor and studied with photoionization mass spectrometry. The photoionization efficiency spectra of these complexes were measured and the ionization threshold energies were determined by the method of the Watanabe plots. The equilibrium conformation geometries, the harmonic vibrational frequencies, the bond dissociation energies, and the ionization potentials of these complexes were calculated by ab initio molecular orbital methods. The corresponding ionic states of these complexes were also studied. The photoionization threshold energy of the potassium-methanol complex was determined to be 3.78 +/- 0.02 eV. Supported by the theoretical results, the experimental photoionization threshold potential of the cyclic form of the potassium-1,2-ethanediol conformers was determined to be 3.40 eV and the upper bounds of the photoionization threshold potentials for the conformers with concerted-intramolecular hydrogen bonding and the straight-chain conformers were estimated to be 3.60 and 3.67 eV, respectively. The bond dissociation energy of the potassium-methanol complex was determined to be 8.3 +/- 1.1 kcal/mol. The interplay of the potassium complexation bonding and the intramolecular hydrogen bonding and its effects on both the bonding energies and the ionization potentials of the conformers were emphasized.