The Low Temperature Heat Capacity of the layered structure Nd3Ni13-xCoxB2 (x = 0, 1, 3, 6, 8, 11 and 13) solid solutions has been measured from 350 mK to 300 K. For high Co content (x ≥ 8), a hyperfine contribution has been explained as due to hyperfine fields of 112.4 kG for Co and 3.68 MG for Nd. The electronic heat capacity contribution reveals an increase of the density of states at the Fermi level as the Co content is increased. For x = 0 a low dimensionality magnetic transition attributed to the Nd sublattice is observed. The substitution of Ni by Co (1 x < 3) induces interaction disorder on the Nd sublattice. For Nd3Ni13B2 an estimation is given for the molecular field of Hm = 54 kG and the exchange constant of J/kB = 4.1 K.