Abstract: A porous SiO2 xerogel is produced using temporary pore fillers or solid skeletal supports, which are removed by thermal oxidation at the end of the production process (e.g. carbon or organic), by means of a sol-gel-process by subcritical drying of the gel. The SiO2 xerogel includes pores having a pore size from more than 50 nm to less than 1000 nm. The SiO2 xerogel has a density of less than 400 kg/m3, a carbon content of less than 10%, a thermal conductivity at 800° C. below 0.060 W/m*K, a thermal conductivity at 400° C. below 0.040 W/m*K, and a thermal conductivity at 200° C. below 0.030 W/m*K.