This research was aimed to measure the effectiveness of using EZproxy on Single Sign On (SSO) in accessing electronic journals for Library Science students, Diponegoro University, Semarang. The analysis used a descriptive analysis method, which is a method that describes the data to get general conclusions. The sample was conducted by purposive sampling method. Collecting data was conducted by a questionnaire distributed to students as much 80 questionnaires. The results of this study are based on indicators of perceived ease of use resulting in a mean of 82.64% which is categorized as very effective; the perceived usefulness indicator produces the highest mean with a value of 83.80% which is categorized as very effective; behavioral intention to use indicator produces a mean of 79.89% which is categorized as effective; the actual system use indicator produces the lowest mean with a value of 74.7% which is categorized as effective. The results of the calculation of the mean value on all 35 statement items obtained a value of 81.25% which can be interpreted as very effective. So it can be concluded that EZproxy on Undip's E-Journal Single Sign On (SSO) service in accessing electronic journals has reached an effective level.