In this paper, we report a detailed study of the structural, magnetic, and electrical transport properties of nano- and bulk La0.5Sr0.5Ti0.5Co0.5O3 perovskite with the aim to study the effect of size reduction on resistivity and the antiferromagnetic spin order that is seen in the bulk samples of the cobaltites. Both the phases crystallize with orthorhombic structure in the Pbnm space group. Size reduction causes an increase in both the lattice parameters and unit cell volume. The M–H curve of nanosample shows appearance of hysteresis and gives a clear evidence of the formation of ferromagnetic (FM) moments while almost no RT-FM behavior was found for bulk sample. The resistivity of the nanocrystalline sample has been found to be much lower than that of the bulk sample in the entire temperature range of investigation which could be due to the formation of ferromagnetic moments in the nanocrystallites.