INTRODUCTION: Multimodal contrast agents play an important role in early diagnosis of diseases and monitoring the treatment outcomes by increasing the accuracy and clarity of images. METHODS: Herein, a one-step simple hydrothermal route is utilized to prepare the gadolinium-1,4 HBDC- metal-organic framework (Gd-BDC-MOF) nanoparticles decorated with gold nanoclusters. The physicochemical properties of bimetal nanostructures were evaluated, their safety and ability to enhance contrast in both CT and MR imaging were also examined. RESULTS: The spherical nano-sized Au decorated Gd bimetal nanostructures have an average diameter of 64 nm. The presence of both Au and Gd metals in the prepared nanostructure was confirmed using EDAX. The XRD pattern shows that, in the hydrothermal synthesis of two metals using a terephthalic acid linker, gold nanoclusters are decorated onto the gadolinium metal organic framework. The FTIR analysis confirmed the attachment of Gd to the carboxylate group of the organic linker. The bimetal nanostructure sample with a concentration of 40 mM showed similar X-ray attenuation to that of iodine at a concentration of 128 mM. At a magnetic field strength of 1.5 T, the longitudinal relaxivity value of the bimetal nanostructure was determined to be 13.635 mM s. The MTT assay demonstrated the cytocompatibility and safety of the contrast agent synthesized for biomedical applications. CONCLUSION: The fabricated bimetal nanostructure exhibits dose-dependent positive contrast enhancement in both MR and CT imaging techniques, making it a promising candidate for use as a contrast agent in medical applications.