Multiwalled carbon nanotubes (MWCNTs) have been successfully synthesized by using a relatively simple method, known as modified Wolff-Kishner reduction process. Transmission electron microscopy (TEM) has shown the as-prepared MWCNTs possess straight morphologies with average inner and outer diameters, between 2 to 7 nm and 5 to 15 nm, respectively. Ultraviolet-visible (UV-Vis) absorption measurement has been conducted for the first time. The correlation between energy of the π plasmon absorbance (Eπ) and nanotube diameter (dCNT) for the as-prepared MWCNTs shows contradiction to the empirical relationship as Eπ = 4.8 + 0.7 / (dCNT)2. Other optical characteristics like transmittance, reflectance and refraction index also have been studied. This work explores the optical property of the as-prepared MWCNTs and thus provides better understanding about the feasibility of this synthesis technique.