Some 10,000 older people out of the approximately 430,000 who are eligible in the Republic have expressed an interest in the new "all-Ireland" free travel scheme since it began last Monday.
Customers from the Republic wishing to avail of the free travel concession in the North require an electronic "Senior Smartpass", which must be applied for through the Department of Social and Family Affairs.
According to Minister for Social and Family Affairs Séamus Brennan, more than 7,000 senior citizens in the Republic have submitted completed application forms for the electronic cards in recent days. Almost 3,000 have also requested application forms.
The new travel scheme allows individuals aged 66 and over, who are resident in the State, to travel free of charge on all bus and rail services in Northern Ireland. Over-65s in Northern Ireland can also travel free on services participating in the scheme in the South.
In the Republic, more than 430,000 of the 600,000 customers currently in receipt of free travel are aged 66 or over. In the North, some 200,000 senior citizens qualify under the concessionary fares scheme.
Expressing satisfaction with the level of applications to date, Mr Brennan said that it "clearly reflected the popularity of the all-island scheme".
"It is an initiative that will help to build new understandings and friendships throughout the island," he added.