•Effect of sustained loading and environmental conditioning on CFRP strands is studied experimentally.•Evaluation of tensile, shear and bond strength of CFRP strands after conditioning.•Tensile testing of carbon fiber tows and epoxy resin specimens after environmental conditioning.•Durability of CFRP strands was not affected by sustained loading and environmental conditioning. This paper presents a comprehensive research conducted to study the synergistic effect of environmental conditions and sustained loading on the mechanical properties of Carbon Fiber Reinforced Polymer (CFRP) prestressing strands. The environmental conditions included exposure of CFRP strands to alkaline solution and sustained loading at an elevated temperature of 55 °C for 3000 and 7000 h. The sustained loading was equivalent to 65 percent of the guaranteed tensile strength of the strands. Mechanical testing performed on the strands included tensile, shear and bond strength as well as evaluation of the elastic modulus of the CFRP strands as affected by the environmental conditions and sustained loading. Durability of the constituent materials of the CFRP strands was also studied.