A foam includes a cellular structure and having a density of at most 0.50 g/cm3, where the cellular structure is provided by a solid material that includes humins. Such a foam is prepared in a process, which includes: providing a starting material containing humins; and heating the starting material to a temperature in the range of 150 to 450° C. The foam can be used in articles for a variety of applications such as substrate for plant growth, as adsorbent for treating waste water or waste gases, as support for solid catalysts, as insulation material, or packaging material.