This study investigated the production of lightweight aerated alkali-activated slag pastes (LAAASP) using hydrogen peroxide (H2O2). A mixture of sodium hydroxide and sodium silicate solution was used for the activation of slag. Physical, mechanical, and thermal properties of samples cured under different curing conditions were investigated. Various water-to-slag ratios (W/S) and H2O2 contents were used to explore the expansion mechanism of fresh mixtures and to investigate their effect on apparent density. The LAAASP produced were in the apparent density range of 516-1199 kg/m(3 )and had 0.5-30.0 MPa compressive strength. Thermal conductivities of aerated samples varied from 0.117 to 0.206 W/m . K in the dry density range of 480-1098 kg/m(3) and were lower than thermal conductivities reported for autoclaved aerated concrete. The use of more than 0.75% H2O2 by mass of slag was found to be non-essential to achieve low-density pastes. (C) 2018 Elsevier Ltd. All rights reserved.