Handling nuclear metallic waste is a crucial issue for the nuclear industry, notably by using adapted decontamination processes. Colloidal gels can be applied by spraying for nuclear decontamination of large and plane metallic surfaces, such as walls or floors. However, this implementation mode limits their use for the decontamination of inaccessible or complex geometries surfaces. For that purpose, decontamination magnetic gels have been formulated by incorporating magnetite particles in a pre-synthesized colloidal gel able to decontaminate stainless steel. Such gels can thus be attracted by a magnet, allowing remote application to surfaces with limited access. The presence of magnetite particles does not influence the inherent decontamination properties of the gel, but plays a significant role on the spreading properties by increasing the gel viscosity. Then, a linear relationship between the gel thickness and the decontamination possibilities has been highlighted. Furthermore, as the magnetite particles dissolve in the gel with time, spreading properties, and consequently the decontamination properties, are modified. Finally, a formulation compromise has to be found for a long-term storage of the gels, while maintaining their efficiency.