Abstract: The 2-adic complexities of the coordinate sequences derived from single cycle T-functions over were investigated. Let be an integer such that . It is shown that the 2-adic complexity of the th coordinate sequence is upper bounded by . The distribution of the corresponding 2-adic number associated with the th coordinate sequence of all single cycle T-functions was also discussed, which implies that the upper bound is attainable. Moreover, 1-error 2-adic complexity was also studied. It was proved that the 1-error 2-adic complexity of the th coordinate sequence is equal to its 2-adic complexity except for .