Concrete is the most common building material with a high thermal mass, and it is of interest to study how thermal mass of buildings influences such factors as their peak power consumption and their thermal comfort. Lightweight concretes can be produced by using processed natural materials, processed by-products or unprocessed porous materials, depending upon the requirements of density and strength levels.In this study, the thermal conductivity, density and compression strength of some novel lightweight self-compacting concretes (LSCC) were investigated. Thermal conductivity is the property of a material related to heat conduction. It is evaluated primarily by applying Fourier's Law for heat conduction. Heat transfer across materials of high thermal conductivity occurs at a higher rate than across materials of low thermal conductivity. Correspondingly materials of high thermal conductivity are widely used in heat sink applications and materials of low thermal conductivity are used as thermal insulation. The standard ASTM-C177, specifies the test procedure for laboratory measurement of the steady state heat flux through flat, homogenous specimens with their specimens in contact with solid, parallel boundaries held at constant temperature using the guarded hot plate. This method was used to determine the thermal conductivity of concrete specimens. Poly-carboxylate Super-plasticizers is a highly flow-able and non-segregating concrete additive. Self-compacting concrete (SCC) has an ability to flow through congested reinforcements efficiently irrespective of the structure geometry. In the test specimens, the water/cement ratio was 0.45, and between 0.50wt% to 1.5wt% Super-plasticizers was added to gain an acceptable workability. In this study, sand has been replaced by non-aggregated and aggregated LECA, pumice, and perlite. Zeolite and micro silica has been used as partial replacement of Portland cement at ratios of 10%, 15% and 20%. Results indicated that this lightweight SCCs by zeolite or micro silica was not only lighter but had higher compressive strength and lower thermal conductivity in comparison to conventional concrete. Zeolite and micro silica tend to increase compression strength (up to 68%) and thermal conductivity (1.45%) at 10wt%. Super-plasticizers provide a network of covalent coupling among the micro silica and zeolite with LECA particles. This network increases the compressive strength. But when zeolite and micro silica content were higher than 10%, compression strength decreased. Using non-aggregated and aggregated LECA instead of silica aggregates in SCC can reduce concrete density up to 30%. Non-aggregated LECA reduces the thermal conductivity more effectively than LECA aggregates. The reason being that coarse LECA aggregates have more porosity and the coefficient of thermal conductivity is significantly reduced (reduction for non-aggregated LECA is approximately 28% and for aggregated LECA is 17%). Density of concrete depends on its components. Compressive strength of concrete containing non-aggregated LECA is approximately 20% lower than concrete containing aggregated LECA. This is due to the fact that strength of concrete is proportional to its density. Compared to conventional concrete, pumice concrete is approximately six times lighter. Thermal conductivity and compressive strength of concrete containing pumice was almost the same as aggregated LECA concrete. Perlite is a volcanic rock with acidic to intermediate composition which forms in the wet condition or aqueous environment. Perlite tends to decrease compression strength, thermal conductivity and density of concrete. When 10% micro silica, 20% perlite and LECA aggregates were used to make the specimens, thermal conductivity decreased more than 31% and density decreased more than 51%. Key Words : Thermal conductivity, Compressive strength, Lightweight self-compacting concrete, Guarded hot plate apparatus, LECA, Pumice, Perlite.