CdSe nanoparticles were electrodeposited on mechanically strained gold, the latter achieved by controlled bending of gold films evaporated on mica. It is shown that the size and bandgap of the electrodeposited CdSe quantum dots (QDs) can be varied by applying mechanical strain to the Au substrate during deposition. This is attributed to change in the lattice spacing of the strained {111} Au and consequently in the lattice mismatch between the Au and the CdSe. Negative mechanical strain promotes the formation of rocksalt (RS) CdSe nanocrystals, normally existing only at high pressures. This is attributed to surface tension compression in the small crystals, together with enhancement of the phase transition by the CdSe/substrate interface.