Nanocrystalline SnO and $SnO_{2}$ powder have been prepared by hydrazine method. Sn-Hydrazine complex was formed by the reduction between aqueous $SnCl_{2}$ solution and hydrazine monohydrate. $SnO_{2}$ nano powder was prepared by the decomposition of Sn-Hydrazine complex at $450^{circ}C$. When NaOH was added to Sn-hydrazine complex, SnO powder with nano-sheet morphology could be prepared. This can be attributed to the role of $OH^{-}$ ion as a reducing agent.