Abstract RESIK is a Bragg bent crystal X-ray spectrometer on board the CORONAS-F satellite. Between 24 August 2002 and 22 May 2003 RESIK collected a large number of solar X-ray spectra in four energy bands covering the range 3.2–6.1 Å. A recent absolute calibration has allowed us to make detailed identification of observed spectral features, and from observed line and continuum fluxes to get temperature, emission measure, etc. The lines were identified using spectra averaged over periods of various solar activity levels. These averaged spectra contain a number of strong lines with transitions in H- and He-like ions of K, Ar, S and Si. Some of them are resonance parent lines and their satellites which were observed with other spectrometers and have been described elsewhere. Here, we report detection of several lines not previously observed in solar spectra, including lines of H-like and He-like S and Si ions with transitions 1s– np and 1s 2–1s np, n up to 10. In addition we provide identification of the He-like Cl (Cl xvi) triplet in the range 4.43–4.45 Å. The feature at 4.182 Å, which is the wavelength of the H-like Cl (Cl xvii) Lyα line, is probably a blend of S xiv satellites from cooler plasma.