The crystal structures of the double tungstates NaM(WO 4 ) 2 with M=Fe, Cr and their solid solution are similar to the wolframite-type structure in the space group P2/c, but with doubled a lattice parameter. Magnetization and neutron-diffraction data reveal that NaFe(WO 4 ) 2 orders antiferromagnetically below 5K with a commensurate propagation vector k=(12,12,12) and magnetic moments of Fe 3+ ions oriented along the a-axis. NaCr(WO 4 ) 2 is antiferromagnetic below 10K. Its magnetic structure is based on the propagation vector k=(12,12,0), and the magnetic moments of Cr 3+ ions are aligned along the b-axis. The magnetic structure in the bc-plane is explained by a supersuperexchange mechanism. Long-range magnetic superexchange interactions along paths including [NaO 6 ]-octahedra are necessary to explain the observed magnetic structures. Mixed NaFe x Cr 1− x (WO 4 ) 2 , with x=0.25, 0.5, 0.75, do not indicate magnetic order, neither in magnetization nor neutron-diffraction data.