The 1201-type Hg–Sr-based cuprates with nominal composition of (Hg_1−xMo_x)Sr₂CuO_4+δ;x=0.15, 0.25 and 0.30, were prepared in partial vacuum. XRD data confirms that they are 1201-type structure. The ac-susceptibility measurements of the samples show that for the composition x=0.15 has a maximum T_c ^onset of∼66 K, whilex=0.25 exhibits T_c^onset of∼50 K. For x=0.30, the observed T_c^onset  of∼36 K is at variance with that reported in literature.