One-Step Blue® is a ready-to-use protein gel staining solution. It produces fast (5-60 min) protein staining in a single step without fixation or washing. Proteins can be detected by visible blue staining, or by near-infrared fluorescence. In addition to rapid results and simple staining, One-Step Blue® offers safer handling and disposal compared to Coomassie staining because it is entirely aqueous-based, without hazardous methanol or acetic acid. One-Step Bluu® has comparable sensitivity as the widely used Coomassie Blue, with a lower limit of detection around 10-20 ng depending on the detection method used. The staining is fully compatible with mass spectrometry and Edman-based sequencing.