The Upper Cretaceous eastern Pontide island arc sequence in northeastern Turkey is composed mainly of volcanic and volcaniclastic rocks and rarely of sediments. In this study, source rock characteristics and hydrocarbon potentials of shale and claystone sequences at Zigana, Catak, and Hacimehmet areas of the volcanic island arc were investigated. According to pyrolysis data, Zigana, Catak, and Hacimehmet sequences show poor source rock character and they mostly contain residual organic matter and type III kerogen. In addition, shales have low potential yield and hydrogen index values. In the burial diagram drawn on the basis of Lopatin method, Sigma TTI values of the Zigana, Catak, and Hacimehmet sequences are calculated as 93,222, 1,124 and 1, respectively. This diagram indicates that Zigana and Catak sequences are out of oil generation zone while Hacimehmet sequence has not reached oil generation zone. T-max values measured from pyrolysis data generally show over mature character for the Zigana and Catak sequences and immature character for the Hacimehmet sequence. T-max values are consistent with burial diagram. Irregularities and deviations observed particularly in Zigana and Catak sequences may be explained with thermal effect of Late Cretaceous volcanism.