Polymer-based high dielectric composites have attracted considerable research attention due to their unique advantages in electronic applications. Polyimide (PI) is a class of high-performance polymers with improved heat-resistance and mechanical properties owing to its aromatic and heteroatomic functionalities, yielding an ideal material for high-temperature applications. In this paper, STRG (solvothermally reduced graphene oxide) was prepared and introduced into PI matrix by solution blending, and the dielectric, mechanical and thermal properties of these STRG/PI composites were studied. The STRG/PI composite (1 wt%) witnessed a significant increase by a factor of 23 in dielectric constant (71 at 10(3) Hz), compared to neat PI. In addition, the tensile strength of STRG/PI composites was improved by 105%. This study demonstrated a promising strategic approach to fabricate STRG/PI composites with enhanced dielectric and mechanical properties, serving potential candidates for high-temperature and high-dielectric applications. (C) 2015 Elsevier Ltd. All rights reserved.