A biological decontamination gel is provided, consisting of a colloidal solution comprising 5% to 30% by mass, preferably 5% to 25% by mass, still more preferably 8% to 20% by mass based on the mass of the gel, of at least one inorganic viscosifying agent an active biological decontamination agent consisting of the combination of a mineral base selected from hydroxides of alkaline metals, hydroxides of earth alkaline metals, and mixtures thereof, and of an oxidizing agent stable in a basic medium selected from permanganates, persulfates, ozone, hypochlorites, and mixtures thereof the mineral base being present in an amount from 0.05 to 10 mol/L of gel, preferably in an amount from 0.1 to 5 mol/L of gel, and the oxidizing agent stable in a basic medium being present in an amount from 0.05 to 5 mol/L of gel, preferably from 0.1 to 2 mol/L of gel optionally 0.1% to 2% by mass based on the mass of the gel, of at least one surfactant and the balance of solvent and the gel not containing any super-absorbent polymer.
