The subject of this doctoral thesis is the application of hot alkali vapors. The thesis is composed of three parts each of which represents a certain application of alkali vapors. In the first part, properties, possible applications and improvements of cesium high pressure light source were studied. Furthermore, the comparison with properties of sodium high pressure light source was made. It was confirmed that cesium light source is, in a spectral aspect, ideal source of light giving that it has a spectrum very similar to the sun spectrum. However its poor efficiency, due to large infrared part of spectrum, has resulted in lack of its wide spread application. Additionally, within the scopes of this research, it was shown that the proportion of infrared part of the spectrum is considerably higher in cesium than in sodium high pressure light source, and that this proportion lowers with lowering voltage. Results of the measurements on the cesium high pressure light source presented in this dissertation could be used in creation of new light sources as well as in certain novel applications, such as generating electrical energy through the conversion of the sun light. The second part of the dissertation included realization of the experimental setup for velocity comb on potassium and theoretical simulation of this result. After previous realization of the femtosecond pulses interaction with the rubidium and cesium atoms, the same was achieved with potassium using the technique of modified direct frequency comb spectroscopy. The assumption that the excited states cannot be relaxed between two subsequent pulses of the femtosecond laser (period of repetition was 12,5 ns) was confirmed. Consequence of this is a change in the structure of the Doppler profile of potassium resonant spectral lines. The theoretical model has shown very good agreement with the experimental results which is of great importance for this method and further possible applications. The same experiment was performed in the homogenous magnetic field. These results could be used for application of potassium in magnetometry. The last part of the doctoral thesis is based on the measurement of absorption spectrum of alkali mixture of rubidium and cesium, or potassium and rubidium at different temperatures. At higher temperatures (higher than 450°C) new spectral phenomena was observed (at 418,3 nm and about 527 nm). They were attributed to molecular satellite of RbCs molecule in the Rb-Cs vapor mixture. In the case of K-Rb mixture several new possible satellites were found which needs theoretical confirmation. Appearance of these new satellites is related to photoassociation of cesium and rubidium, or potassium and rubidium atoms. Confirmation of their existence is very important for applications in physics of ultracold molecules. As an overall conclusion, it is possible to expect the application of alkali vapors in several areas; in the field of development of new light sources, interacting femtosecond laser frequency comb with potassium atoms in a magnetic field, as well as in the domain of heteronuclear molecules with new satellite bands.