The oxide scale present on the feedstock particles is critical for inter-particle bond formation in the cold spray (CS) coating process,therefore,oxide scale break-up is a prerequisite for clean metallic contact which greatly improves the quality of inter-particle bonding within the deposited coating.In general,a spray powder which contains a thicker oxide scale on its surface (i.e.,powders having high oxygen content) requires a higher critical particle velocity for coating formation,which also lowers the deposition efficiency (DE) making the whole process a challenging task.In this work,it is reported for the first time that an artificially oxidized copper (Cu) powder containing a high oxygen content of 0.81 wt.％ with a thick surface oxide scale of 0.71 μm.,can help achieve an astonishing increment in DE.A transition ofsurficial oxide scale evolution starting with crack initiations followed by segmenting to peeling-off was observed during the high velocity particle impact of the particles,which helps in achieving an astounding increment in DE.Single-particle deposit observations revealed that the thick oxide scale peels off from most of the sprayed powder surfaces during the high-velocity impact,which leaves a clean metallic surface on the deposited particle.This makes the successive particles to bond easily and thus leads to a higher DE.Further,owning to the peeling-offof the oxide scale from the feedstock particles,very few discontinuous oxide scale segments are retained at inter-particle boundaries ensuring a high electrical conductivity within the resulting deposit.Dependency of the oxide scale threshold thickness for peeling-off during the high velocity particle impact was also investigated.