The phase formations and the magnetic properties of the mechanically milled NdFe_11−yCo_yMo₁N_x (y=0, 0.5, 1, 1.6, 2.2) compounds have been studied. A relatively high remanence to saturation magnetization ratio of 0.6-0.7 and a high coercivity up to 9.5 kOe were achieved for these nitrides. It is found that the substitution of Co for Fe plays a key role in the grain growth and the grain distribution of α-Fe. The remanences and the coercivities of these compounds increase with the Co content up to y ≤ 1.6. These compounds show a significant remanence enhancement which can be attributed to the magnetic exchange coupling between Nd(Fe,Mo)₁₂N_x and the α-Fe(Co) grains. The maximum energy product (BH)_max of about 8.3 MG Oe is obtained for NdFe₁₀Co₁Mo₁N_x with a H_c of  ∼  9.5 kOe and a M_r of  ∼ 78 emu/g.