Optical, magnetoresistance, and thermoelectric of La1-xKxMnO3 (x= 0.05, 0.15 and 0.25 at%) compounds have been investigated. The crystallography demonstrated that the samples × = 0.05 and 0.15 are a single-phase rhombohedral ( R 3 ¯ C $R \bar{3} C$ ) structure, while x= 0.25 is near to a single rhombohedral phase with a minor amount of Mn3O4 (with a ratio of ∽ 2%). The optical properties manifested that the reflectivity decreases slightly with increasing x-doping, where the sample of x=0.05 has the lowest reflection value, making it a promising material for photovoltaic applications. Electrical resistivity measurements show that the samples have a metal-semiconductor transition, and the transition temperature Tms decreases with the K content. The thermoelectric data shows a remarkable coincidence behavior of the ρ-T relationship, which has a peak at a transition temperature (TS). Magnetic susceptibility data show that the samples undergo Ferro- paramagnetic transition at a certain temperature (Curie temperature).