The present invention relates to a process for producing porous materials, which comprises providing a mixture comprising a composition (A) comprising components suitable to form an organic gel and a solvent mixture (B), reacting the components in the composition (A) in the presence of the solvent mixture (B) to form a gel and drying of the gel, wherein the solvent mixture (B) is a mixture of at least two solvents and the solvent mixture has a Hansen solubility parameter δH in the range of 3.0 to 5.0 MPa−1, determined using the parameter δH of each solvent of the solvent mixture (B). The invention further relates to the porous materials which can be obtained in this way and the use of the porous materials as thermal insulation material and in vacuum insulation panels.