Fission and cluster decay is studied for ⁵⁶ Ni^* produced as an excited compound system in heavy-ion reactions. For the dynamical collective mass transfer assumed for the fission of ⁵⁶ Ni^* , the calculated fission mass distribution matches the experimental data nicely, showing clearly an asymmetric mass distribution preferring the -nuclei fragments. Orbital angular momentum effects are also included. Since the shell effects are almost zero at the excitation energies involved, the -nucleus structure in the fission mass distribution of the ⁵⁶ Ni^* system is apparently due to the macroscopic energy, taken from the 1995 binding energy tables of Möller et al (Möller P, Nix J R, Myers W D and Swiatecki W J 1995 At. Data Nucl. Data Tables 58 185). The cluster decay process is studied within the preformed cluster model and its simplification to the unified fission model. The two processes of binary fission and cluster decay are shown to be almost indistinguishable, particularly at higher angular momenta. The role of total kinetic energy of fragments seems evident for the -nucleus structure effect in the decay constant.