The partial phase diagram of $NaNO_3$-NaCl system was investigated and the eutectic temperature was determined as $294.5^{circ}C$. A typical rod eutectics of $NaNO_3$-4.56 wt%NaCl was directionally solidified. The results of interrod spacing, ${lambda}_E$ as a function of growth velocity, V, were. obtained as ${lambda}_E;V^{0.39};=;5.26$ (temperature gradient, $G_l;=;21.4^{circ}C/mm$) and ${lambda}_E;V^{0.32};=;5.45$ ($G_l;=;3.9^{circ}C/mm$) and the exponent numbers of growth velocity were smaller than the theoretical value, 1/2. The sample rotation applied during directional solidification made the interrod spacing decrease slightly.