Error estimates in L∞(0,T;L2(Ω)), L∞(0,T;L2(Ω)2), L∞(0,T;L∞(Ω)), L∞(0,T;L∞(Ω)2), Ω in ${ℝ}^2$, are derived for a mixed finite element method for the initial-boundary value problem for integro-differential equation $$u_t=\mathrm{div}\{a▽u+{\int }_0^t{b}_1▽u\mathrm{d}\tau +{\int }_0^t𝐜u\mathrm{d}\tau \}+f$$ based on the Raviart-Thomas space Vh x Wh ⊂ H(div;Ω) x L2(Ω). Optimal order estimates are obtained for the approximation of u,ut in L∞(0,T;L2(Ω)) and the associated velocity p in L∞(0,T;L2(Ω)2), divp in L∞(0,T;L2(Ω)). Quasi-optimal order estimates are obtained for the approximation...