Carbon nanotubes (CNT) have seen a wide variety of applications, spread well beyond the semiconductor industries - especially in field emission related devices. For its widest possible application, it has become very much important to grow CNTs on a variety of metallic substrates and understand their field emission response. In the present study, multiwall CNTs (MWCNT), grown on pure metallic substrates like Cu, Al and W, were subjected to field emission tests under DC and AC bias. Choice of diffusion barrier layer and catalyst was also varied, to verify their effects on the emission response. Field emission behaviors from all such structures were compared with MWCNTs grown on Si. It was found that the MWCNTs grown on pure Cu substrate showed excellent field electron emission response, in terms of low turn-on field, high emission current, long time stability and very high field enhancement factor.