Hi Bhanu,
One can specify type of Serialization as a decorator or in web.config of the wcf service.Please read below article for detailed explantion of serialization.
http://msdn.microsoft.com/en-us/magazine/cc163569.aspx[
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Example :
[XmlSerializerFormat]
[ServiceContract]
public interface IEchoService
{
[DataContractFormat]
[OperationContract]
Person EchoPerson(Person person);
[OperationContract]
Address EchoAddress(Address address);
[OperationContract]
Phone EchoPhone(Phone phone);
}