A simple, cheap and portable spectrophotometric system is described. It is based on the use of a cheap digital microscope housed from a 3D printed device which simultaneously supports a LED as a light source and a flow cell. A simple electronic device to power the LED is also described using electronic smd components. Both the digital microscope and the power source required to light the LED are connected to the USB ports of a notebook in order to avoid the need of any power source to complete the portable system. This method was applied to make the determination of Fe2+ with o-phenanthroline as chromogenic reagent. The reaction provided the red complex which is used to monitor the analytical response with the digital microscope. Portable spectrophotometric device using a digital microscope. A: digital microscope; B: 3D printed support of the digital microscope, cell and light source; C: cuvette; D: Head for LED; E: regulated voltage power supply; F: USB digital microscope connection; G: USB regulated voltage power source connection. Display omitted •A cheap, simple and portable spectrophotometric system has been developed using a digital microscope.•Two USB ports of a laptop are used to power the microscope and the radiation source.•A simple electronic device connected to an USB port has been used to power different kind of LEDs used as radiation source.