Hi Mahendra:
Certification for Ariba Procure to Pay launched last month. You can learn more at this blog post: http://scn.sap.com/community/training-and-education/certification/blog/2016/04/20/sap-ariba-has-arrived-with-certification-in-the-cloud-for-ariba-procure-to-pay
Good luck!
Debbie Curtis-Magley
SAP Ariba Exchange Community Manager