IntroductionThe insertion of a peripheral venous line is of paramount importance in the stabilisation of critically ill patients. It is a preferred method of venous access over more invasive techniques due to its immediacy and fewer complications. Difficulties of catheterisation can result in delays to treatment, increased complication risks and pain, and a waste of valuable time and healthcare resources. Our hypothesis is that infrared vein illumination could improve the success rate of peripheral venous catheterisation in critically ill patients at risk of difficult catheterisation.Methods and analysisThis is a prospective, multicentre, randomised, open-label controlled trial. It will be conducted in France and will involve critically ill patients at risk of difficult peripheral catheterisation. Patients will be randomly assigned to usual care or infrared vein illumination. The primary outcome is the rate of successful peripheral venous catheterisation at first puncture. Secondary outcomes include time to placement, overall rate of successful peripheral venous catheterisation, number of punctures, quality (calibre of the catheter), replacement rate, need for central line and local complications (dysfunction, diffusion, haematoma and lymphangitis).Ethics and disseminationThe study has been granted ethical approval (CPP Ile de France 1). Following the provision of informed consent, patients will be included in the study. The results will be submitted for publication in peer-reviewed journals.Trial registration numberNCT03932214.