AdBlue is a synthetic solution of urea and demineralized water that is used in modern diesel vehicles with SCR (Selective Catalytic Reduction) technology to reduce harmful nitrogen oxides (NOx) in exhaust gases. It is not a fuel additive and is poured into a special, usually blue, tank.

AdBlue is a non-toxic, colorless and environmentally friendly fluid consisting of 32.5% of high-purity urea and 67.5% demineralized water. Its primary function is to enable diesel engines (typically Euro 4, Euro 5 and Euro 6 standards) to meet strict environmental regulations.