INTRODUCTION: Each human action involving tools requires transformations of motor responses of hands/ fingers (or different effectors) into mechanical actions of a tool. Whereas tools requiring a relatively low level of motor-to-mechanical transformations were extensively studied, little is known about the neural underpinnings of complex tool use, which involves compound motor‑to‑mechanical transformations. AIM(S): The aim of this study was to investigate the neural bases and mechanisms of functional interactions with tools that are characterized by a high level of motor‑to‑mechanical transformations. METHOD(S): Functional magnetic resonance imaging (fMRI) was utilized in 20 right-handed participants when they prepared and performed multi-phase purposeful actions with real complex tools, with their right and left hands. Specifically, neural activity was investigated during the planning and execution of functional grasp and subsequent usage of complex tools, as compared to actions involving simple tools and control, non‑tool objects. RESULTS: Although specific neural engagement for complex tools, as compared to non-tools, was observed in all phases and concerned nodes of the left-lateralized Praxis Representation Network (PRN), complex tools vs. simple tools, were processed differently at the grasping and tool‑use programming stage. In this phase, the grasping action directed at complex tools involved more the intraparietal sulcus and the nearby subdivisions of the superior parietal lobule. Interestingly, more thorough analyses demonstrated that such translations from motor to mechanical codes also engaged the rostral inferior parietal lobule. CONCLUSIONS: These outcomes point to the prospective character of grasp coding, a process associated with the activity of the intraparietal sulcus, and its cooperation with other hand-centered and tool-centered mechanisms during performance of motor-to-mechanical transformations. FINANCIAL SUPPORT: Supported by NCN Maestro 2011/02/A/HS6/00174 to GK.