for the temperature of the heat treatment which was 500 u00b0 c for the obtained activated carbon the following values were determined the process was carried out as described under example 1 instead of htc carbon from cherry stones htc carbon from hazelnut shells was used the yield was approximately 12 for the obtained activated carbon the following values were determined the process was carried out as described under example 1 instead of htc carbon from cherry stones htc carbon from coconut shells was used the yield was approximately 30 the specific bet surface reached 2 579 m 2 g htc carbon from cherry stones was activated in an aqueous solution of 0 5 m 1 m or 2 m potassium hydroxide at 30 u00b0 c then the potassium hydroxide solution was filtered off the reaction product was washed with deionized water and dried in an oven at 105 u00b0 c for several hours in a determination of the specific surface according to the bet method the obtained reaction produce did not exhibit any significant increase of the specific surface cherry stones with a water content of approximately 60 relative to the dry substance were used for the production of the htc carbon the table 1 shows the composition of the cherry stones the cherry stones were subjected to a hydrothermal carbonization with water and under pressure for one hour at 160 u00b0 c and then for 5 hours at 220 u00b0 c.