Weed seeds can remain viable in the soil for many years. In the seed bank, that is, the place where weed seeds are kept until they germinate and germinate, there are various types of weed seeds that have different germination abilities. Some species can germinate even after surviving unfavorable conditions, and some lose the ability to germinate after the same. The viability of weed seeds is a key factor in control because there is a potential possibility of further spread and reproduction of the weeds we want to control. One of the potential methods to prevent the spread of not only weeds but also other harmful organisms is soil sterilization. Exposure of the soil to high temperatures leads to the death of temperature-sensitive weed species, which reduces the seed population in the soil seed bank. The goal of the research is to determine the lethal temperature and length of soil exposure for the weed species Amaranthus retroflexus L. by applying different temperatures (40, 50, 60, 80, 100, 120°C) at different lengths of soil exposure (30, 60 and 90 min). and Setaria pumila (L.) P. Beauv. Determination of the lethal temperature and duration of exposure is a contribution to the development of soil sterilization methods used in in situ experiments without the presence of viable weed seeds. The results of the research show that high temperatures can destroy and increase the mortality of weed species in the soil we are sterilizing.