Layered structure of highly crystalline orthorhombic GaOOH nanorods undergo significant lattice distortions leading to amorphisation even when very small amounts of Eu³⁺ ions (1 at.% or more) are present during its synthesis. Local short range order around Ga³⁺ is unaffected by the structural collapse, even though the lattice disorder increases with increase in Eu³⁺ content in the lattice, as confirmed from the EXAFS studies. Incorporation of Eu³⁺ ions at the interlayer spacing of GaOOH lattice and its reaction with structure stabilizing OH linkages in the lattice is responsible for the collapse of the structure leading to amorphisation.