Abstract. We consider the Dunkl intertwining operator V α and its dual t V α , we define and study the Dunkl Sonine operator and its dual on R. Next, we introduce complex powers of the Dunkl Laplacian ∆ α and establish inversion formulas for the Dunkl Sonine operator S α,β and its dual t S α,β . Also, we give a Plancherel formula for the operator t S α,β .