This PhD thesis presents new polyurethane foams with a polar surface-active component that have other morphological and thermal properties than conventional PU foams do have. The novel PU foams were produced with polar additives and tested for thermal properties, showing successful results. The modification of PU foam with polar azo components has not been considered in the published literature yet. These azo components, indeed, possess some special properties, they are polar, water-soluble, surface-active, light sensitive and non-toxic. Hence, a new PU foam based on commercial polyols and isocyanates with a novel synthesized azo polyol was developed to achieve enhanced thermal properties. The selection of the modified system in this work was based on the required foam properties and processing, therefore a polar 3-carboxyphenyl-azosulphonate was chemically bonded to the standard polyol in such a way that it does not react with isocyanate during PU foam manufacturing. For the manufacturing of foams under laboratory conditions, the components of the reagent mixture were consequently premixed with each other by an automatic mixer. Taking into account the importance of foam cell gas analysis, an improved gas chromatography-mass spectrometry (GC-MS) method for detection of foam cell gas content was developed. The effect of additive incorporation and mixing parameters on foam kinetics, cellular structure, foam gas phase and the overall thermal conductivity of the foam was investigated as well.