Let C be a smooth projective curve of genus
$2$
. Following a method by O’Grady, we construct a semismall desingularisation
$\tilde {\mathcal {M}}_{Dol}^G$
of the moduli space
$\mathcal {M}_{Dol}^G$
of semistable G-Higgs bundles of degree 0 for
$G=\mathrm {GL}(2,\mathbb {C}), \mathrm {SL}(2,\mathbb {C})$
. By the decomposition theorem of Beilinson, Bernstein and Deligne, one can write the cohomology of
$\tilde {\mathcal {M}}_{Dol}^G$
as a direct sum of the intersection cohomology of
$\mathcal {M}_{Dol}^G$
plus other summands supported on the singular locus. We use this splitting to compute the intersection cohomology of
$\mathcal {M}_{Dol}^G$
and prove that the mixed Hodge structure on it is pure, in analogy with what happens to ordinary cohomology in the smooth case of coprime rank and degree.