The invention relates to a composition used as a fire-resistant, insulating, ecological and corrosion-inhibiting coating, comprising: 23-50% water, 4-20% diatomite C110 (Celite C110®), 2-8% manganese oxide, 3-10% calcined alumina, 7-24% elastomeric acrylic resin, 1-4% acrylic thickener, 0.3-2% ammonium hydroxide, and 5-14% ceramic fiber. Preferably, the composition also includes optionally the following components in order to provide the fire-resistant, insulating, ecological and corrosion-inhibiting properties: 1-7% titanium bioxide, 1-9% hexylenglycol, 2-18% dibutyl phthalate, 1-9% texanol, 0.7-4% fungicide, or 0.4-3% anti-foaming agent.