Despite the prominence of cyanoacetylene as an important prebiotic molecule, experimental data for HC 3 N is sparse and there exists no comprehensive line list . While HC 3 N has been investigated in the past, it has been almost exclusively at room temperature in the mid-to-far infrared regions , with no available data for the near infrared. With the estimates obtained in this work, we fill this gap and further propose this spectral region as an observational target for HC 3 N in exoplanetary atmospheres. By way of comparison, the combination band of H 2 S is a target for detection in this spectral region by the Near Infrared Imager and Slitless Spectrograph (NIRISS) system on the JWST on several model exoplanetary bodiesincluding Hycean and Super-Earths, where cyanoacetylene is expected . The vibrational band strength presented here for HC 3 N at 1.5 µm (∼ 10 -19 cm -1 /( molecule • cm -2 )) is larger than that of H 2 S (∼ 10 -20 cm -1 /( molecule • cm -2 )) near 1.6 µm . HC 3 N can therefore be expected to have even better detection thresholds to those of H 2 S of 10-100 ppm expected using the NIRISS.