Ultrashort laser pulses emitted by a neodymium glass laser system were focused on the surface of solid targets situated in a high‐vacuum environment. The laser pulse duration as measured by the two‐photon fluorescence technique was less than 10−11sec. Pulse energies up to 3 J were obtained corresponding to a maximum energy release of 3×104J cm−2in the focal area. The plasmas produced from targets of solid deuterium, carbon, and thin foils of Mylar were investigated by x‐ray measurements, time‐of‐flight measurements using charge collecting probes, and, in the case of deuterium, by neutron counting measurements. Only 10% of the incident light energy was found to be reflected from the targets. Electron temperatures of 500 and 200 eV were measured for deuterium and carbon plasmas, respectively. The experimental results are found to be consistent with the predictions of the model of a thermal wave penetrating into the solid.