In this study we show the results for parametric non-degenerate four wave mixing (FWM) obtained using double lambda scheme at D1 line in hot potassium vapor. We have investigated the influence of one-photon detuning and two-photon detuning on the FWM gain. The laser frequency is locked at approximately 1GHz from the resonance 4S<sub>1/2</sub> F<sub>g</sub>=1 -< 4P<sub>1/2</sub>, using external reference cavity. The probe beam passes through acoustooptic modulator that enables controllable detuning around 460 MHz (ground state hyperfine splitting) in respect to the pump beam. The vacuum glass cell containing the potassium vapor was heated by hot air in order to achieve necessary concentration of atoms. The efficiency of FWM process is studied by measuring the gains of the conjugate beam the probe beam, simultaneously. The maximal gain was achieved for nonzero two photon detuning.