Potassium (K)-induced structural and electronic modifications in the copper hexadecafluorophthalocyanine (F16CuPc) monolayer were investigated by scanning tunneling microscopy and photoemission spectroscopy. The adsorption of K was found to cause a rearrangement of the molecular ordering in the F16CuPc monolayer, depending on the K concentration. For doping with one to two K atoms per molecule, K adsorbs in the intermolecular region adjacent to the aza-bridging nitrogen, forming new ordered phases. A further increase in K coverage causes the on-top adsorption of K, which in turn disorders the monolayer. The photoemission spectrum of the K-doped phase exhibits a small density of states immediately below the Fermi level. Both the formation of the new states and the K-induced structural ordering or disordering of the molecular layer may be responsible for the reported alteration of the macroscopic electronic conductivity.