A single - pot improved process for preparing irinotecan comprising the fallowing steps, taking a mixture of dimethyl carbonate with 4-piperidinopiperidine and 7-ethyl-10-hydroxycampotothecin treated with a base at a temperature between 35 c for a period of 36 hours, until to form organic layer, the said organic layer is treated with water and allowed to distillation under vaccaum, further methanol is added within 30 minutes at refluxing, the resulting mixture is allowed to cool to 2 to 6 c following constant stirring at the same temperature until to form suspension, the said suspension further allowed to cool at 0 C with a stirring for a period of atleast 1 hour the resultant product is subsequently filtered off and dried in vaccaum, produces irinotecan base the said product is crystallized using 2-methoxy ethanol.
