Summary: We obtain the sequential labelling for graphs \(P_m \times C_n\), \(I(P_m\times C_n)\) and \(W(m, n)\). It is proved that \(P_m \times C_n\), \(I(P_m\times C_n)\) and \(W(m, n)\) (\(m \geq 1\), \(n \geq 3\) and \(n\) is odd) are sequential graphs and are also harmonious.