Polyols based on natural oils (NOPs) can be used in formulations of various polyurethane materials including foams with the cell structure and properties required for their typical applications. Vegetable oils such as rapeseed, soybean, sunflower and linseed oils may be applied as raw materials but first, they need to be transformed. The transformations of the double bonds of triglycerides to hydroxyls make such products capable for reaction with isocyanates. Taking into account that European countries have a vast potential regarding cultivation of oil plants, the investigations may result in a significant source of modern, sustainable, and more ecological polymers. In the presented work, the properties of various polyurethane foams modified with NOPs were investigated. The cellular materials with apparent densities ca. 27–43 kg/m3 were moulded. The influence of the type and amount of oil-based polyol on cell structure, mechanical and heat insulating properties of the foams is discussed.