The electrical resistivity ρ, thermal conductivity κ, and thermoelectric power S have been measured for two bare K specimens between 80 and 330 K. The data fully support the main conclusions of an earlier, preliminary study by Cook and Laubitz. The Lorenz function L = κρ/T does not approach the Sommerfeld value L0 with increasing temperature. Both the magnitude and temperature dependence of L–L0 indicate the presence of an added term Wee in the thermal resistivity, due to electron–electron scattering. Such scattering also affects S. It is shown that the data for K, together with published values of B = Wee/T for Na, Rb, and the noble metals, form a consistent picture of electron–electron scattering in the monovalent metals above the Debye temperature.