The rising global temperature is partly associated with the increase of anthropogenic carbon dioxide (CO2) emissions. Major part of this CO2 comes from building material industry and from energy consumed to maintain buildings. To solve this problem a building material that both has low thermal conductivity and emits low amount of CO2 is needed. Hemp and hydraulic lime building materials are one of these materials, but they are not widely used partly due to insufficient research of their possible properties. The aim of this research was to find optimal composition of artificial hydraulic lime binder and to elaborate appropriate compositions of hemp-lime insulating material. The binder itself was also to be tested as multiple air limes were supplemented with different additives and the most appropriate for use in hemp-lime material was to be chosen – a dolomitic lime DL60 with 40% metakaolin additive. The ratio of hemp/binder 0.38 gave the best results – compressive strength of 0.221 MPa at 10% deformation and thermal conductivity of 0.0757 W/m2k, which is considered a good result and shows a possibility for this material to be used as self-bearing thermal insulation building material.