Multi-principle element alloy FeCoNiCu with varying Sn addition was undercooled using the meltfluxing technique to illustrate the dependence of growth kinetics on Sn addition. The alloy FeCoNiCuSn0.5 shows morphological variation in the microstructure from dendritic to equiaxed grain morphology with the increase in undercooling. The alloy FeCoNiCuSn5 shows dendrite morphology with undercooling. The dendritic growth velocity was sluggish with solute addition,i.e., at an undercooling of 200 K, the growth velocity decreased from 25 m/s to 6 m/s while varying Sn concentration from 0.5 to 5 at % suggesting solute drag effect. The microhardness improvement could be correlated to the microstructure refinement achieved during undercooling. © 2020