The author considers the operator \(A_W\) on \(C([0,1])\) defined by: \[ \begin{cases} {\mathcal D}(A_W): =\biggl\{u\in C^2\bigl( [0,1]\bigr) \mid(au')'(j)+ \beta_j u'(j)+ \gamma_ju(j)=0,\;j=0,1\biggr\}\\ A_Wu:=(au')',\end{cases} \] where \(\beta_j\), \(\gamma_j\) \((j=0,1)\) are arbitrary real numbers and the function \(a\in C^1([0,1])\) satisfies \(a(x)\geq a_0>0\). Such operator \(A_W\) is called the realization of the operator \((au')'\) on \(C([0,1])\) with Wentzell-Robin boundary conditions. Using perturbation arguments the author shows that the semigroup generated by \(A_W\) is holomorphic.