[en] Energy spectra of the ground configuration and the first four excited configurations of fluorine-like potassium K XI have been calculated using the configuration interaction method. The wavelengths and transition probabilities of one-electron and two-electron transitions are obtained ab initio. The probabilities of one-electron transitions 2s²2p⁴3p-2s²2p⁴3s and two-electron transitions 2s²2p⁴3p-2s2p⁶ for determination of lifetimes of the levels of configuration 2s²2p⁴3p are used. The calculated results are compared with the recent experimental data and other theoretical results