To get married in the Dominican Republic you will need the following documents:
Complete Original Full Birth Certificate or an Official Extract including parents´ names ; and
According to his/her situation:
If never married: A Statutory Declaration, stamped by a Notary or Solicitor, declaring single marital status and eligibility to marry.
If divorced: Decree Absolute and a Statutory Declaration, stamped by a Notary or Solicitor, declaring marital status and eligibility to marry.
For further details visit http://www.dominicanembassy.org.uk/Marriage.html