Abstract: We have designed and constructed a compact nano-positioning system for a Portable Transmission X-ray Microscope (PTXM). We introduce a concept of PTXM and adopt modular approach which implements identical nano-motion platforms to perform manipulation of PTXM components. Modular design provides higher stiffness of the system and allows for reduction of relative thermal drifts between individual constituents of the PTXM apparatus, ensuring a high degree of stability for nanoscale x-ray imaging. We have measured relative thermal drifts between two identical modules to be as low as 15 nm/h, sufficient to perform nanoscale imaging by TXM. Spatial resolution achieved by developed linear piezo stages was measured to be 3 nm with repeatability of 20 nm over 1 mm travel range.