I have a workflow with some assign flexi tasks in that. Now i want to store the duration taken by each approver in new column in sharepoint 2010.
can some please assist me to proceed further.
afaik there is no ootb functionality to achieve this. However, you can simply use a "Calculate Date" action to save the current date and time to a variable directly before your flexi task. After the flexi task you get the current date and time again and just calculate the difference. You can then store this information in you new column.