The present invention provides a novel melamine-chrome complex comprising imine groups. It is essentially a formaldehyde free chromium complex consisting of a dialdehyde capable of performing rechroming and retanning in a single step. A process for preparing the said eco-benign complex is also provided. The complex is available in both solid as well as liquid form. When applied in leather processing, it confers thermal stability to hides/skins. It also helps in filling the empty regions within the fibre matrix, thereby providing fuller leather.