A debris‐free, narrow‐bandwidth, single‐line laser‐plasma soft x‐ray source has been developed suitable for water‐window microscopy using zone‐plate optics. The 10 Hz table‐top source utilizes microscopic ammonium hydroxide droplets as target. The N VI emission at &lgr;=2.88 nm is ∼1×1012photons/(sr pulse). As an alternative to ammonium hydroxide, it is demonstrated that urea dissolved in water also produces strong emission from nitrogen ions, thereby extending the applicability of the droplet x‐ray source to a new range of target materials. ©1995 American Institute of Physics.