This research aims to compare the quality of cooking oil using the viscosity and refractive index parameters. The sample used was cooking oil which is commonly used in Aceh, namely branded palm oil and coconut oil. Each sample was varied into three types, namely new cooking oil, once used and twice used. Measurement of the viscosity and refractive index of cooking oil was carried out at the Physics Education Laboratory of the State Islamic University of Ar-Raniry. Measurement of the viscosity of the sample was carried out using the principle of a falling ball on a glass tube, while the measurement of the refractive index used the principle of light refraction on a hollow glass prism made from ordinary commercial glass sheets. It was obtained that the viscosity of the branded palm oil and coconut oil samples were 0.5515 Pa.s and 0.5178 Pa.s. The refractive index values for branded palm oil and coconut oil samples were 1.5031 and 1.4967. The viscosity and refractive index of coconut oil sample are lower than branded palm oil, so it can be concluded that coconut oil has better quality than branded palm oil. The results of the data analysis also showed that the quality of the two cooking oil samples decreased after repeated use as indicated by the increase in the measured parameter. The branded cooking oil is better to use repeatedly up to two times because it has a minimum increase in viscosity and refractive index compared to coconut oil.