Carbon nanotubes (CNTs) were successfully synthesized using waste cooking palm oil (WCPO) as precursor by modified double-stages thermal chemical vapor deposition set-up. The total amount of 30 ml WCPO precursor was consumed during the experiment with 5.33 wt% ferrocene as catalyst. Precursor volume of 2 ml was injected continuously for different time intervals of 5, 8, 10 and 12 minutes respectively. The effect of time interval between injections on the production of CNTs were systematically studied using field emission scanning electron microscopy, micro-Raman spectroscopy and current-voltage (I-V) measurement system. It was detected that the differences in time interval of injections resulted in different quality and diameter of CNTs produced. Sample produced at 10 minutes of time interval of injection gave the smallest tubes diameter in the range of 39.45-49.01 nm and good crystallinity of 0.69 ID/IG ratio. This sample also gave the best I-V characteristic with conductivity of 6.06 x 10-1 S/cm.