Single-electron transistors (SETs) are used to perform sensitive charge measurements and are widely discussed as possible components of dense integrated circuit. An exact model for a single-electron transistor (SET) was developed [1] early, within the circuit simulation package SPICE; it's constituted by two tunnel junctions, with two gates coupled to the island. We will present here a description of previews results of SET [1] and our perspective for a superconductor single electron transistor. Superconducting single-electron transistors (SSET's) are small islands of superconducting material isolated from an external circuit by tunnel barriers (Josephson junctions). The normal tunnel bar...