Cygnus X‐3, among the X‐ray binaries, is one of the brightest in the radio band, repeatedly exhibiting huge radio flares. The X‐ray spectra shows two definite states, low (correspondingly hard) and high (correspondingly soft). During the hard state the X‐ray spectra shows a pivoting behaviour correlated to the radio emission. In the high state the X‐ray spectra shows a gamut of behaviour which controls the radio flaring activity of the source. The complete evolution of the X‐ray spectra along with the radio flaring activity is reported here, for the first time for this source. © 2004 American Institute of Physics