On the contrary, the concept of non-isothermal growth has been implemented in many other material systems for several decades; it is a well-established technique for the crystallization of polymers, glasses and metals from their molten phases. Both continuous cooling transformation and time-temperature-transformation processes are widely used in metallurgy for inducing metastable phases in steel and other alloys. The transformation kinetics in nonisothermal crystallization follow an exponential growth model first described for isothermal crystallization by Avrami and later extended to non-isothermal growth processes. In the case of nanomaterials, non-isothermal crystallization has been demonstrated for the synthesis of metal oxide and fluoride nanoparticles. These studies showed that morphological control over the resulting product (wire-like vs. particle-like) could be obtained by controlling the precipitation rate, similar to processes observed in steel (for example, martensite vs. bainite formation). One recent study showed that a continuous film of bilayer graphene could be produced through nonisothermal growth when the temperature was lowered from 1000 to 900 ºC at optimal cooling rates and CH4 flow rates. Here we show that CNT yield can be enhanced significantly by dynamically varying the temperature during growth, i.e. by preforming non-isothermal chemical vapor deposition (CVD). This was achieved by continuously cooling the CVD reactor from a high to a low temperature during growth. The yield depends on the temperature difference and cooling rate (time difference), and we show through in situ Raman studies that it is enhanced due to an increase in both CNT growth rate and catalyst lifetime. Moreover, we observed the increase in yield for two common CNT catalysts, Fe and Co and for cold-wall as well as traditional thermal CVD in a tube furnace (referred to as tube furnace CVD hereafter). The enhanced yield is a result of higher particle densities, producing vertically aligned CNT arrays under conditions that would normally produce a sparse mat of CNTs on the substrate. Our results show that non-isothermal CVD is a highly promising method for increasing CNT yields.