The invention relates to a long chain ammonium polyphosphate and its use as an effective additive in lubricants and/or coolants for metal working under extremely high pressures and temperatures. The polyphosphate chain preferably contains 50 to 1000 phosphorus atoms. Up to 20% of the ammonium groups are replaceable by hydrogen. The additive is preferably added to the lubricant/coolant in a proportion of 0.1 to 30 weight %.