A framed symplectic sheaf on a smooth projective surface XX is a torsion-free sheaf EE together with a trivialization on a divisor D⊆XD⊆X and a morphism Λ2E→𝒪X satisfying some additional conditions. We construct a moduli space for framed symplectic sheaves on a surface, and present a detailed study for X=ℙ2ℂ. In this case, the moduli space is irreducible and admits an ADHM-type description and a birational proper map onto the space of framed symplectic ideal instantons.