A promising solution to the environmental instability of semiconducting organic materials is presented. Thin, highly ordered films (see Figure, a scanning probe microscopy image), fibers, and field-effect transistors (FETs), comprising chain-structures based on the so-called Magnus' green salt, [Pt(NH3)(4)]-[PtCl4], were synthesized in aqueous media (see Cover). FETs were manufactured under ambient conditions from common organic solvents, and exposed-without significant loss of performance-to white light and air for periods of time in excess of 6 months, and to water of 90degreesC for more than 12 h.