An organic light emitting display (OLED) device having a demultiplexer and a method of operating the OLED are disclosed. In the OLED device, each pixel column is provided two data lines, and each data line is connected to odd or even row pixels of the column. Accordingly, a data signal can be supplied to one of the data lines during one scan period, and transmitted to the corresponding pixels during a next scan period. Thus, because the data driver is only driving half the pixels of the column, the driving time is reduced.