Try this:

SELECT CONVERT(datetime2, '25/05/2016 09:00', 103)

The convert method takes 3 arguments: The first is the target data type, the second is the expression to convert, and the third is the style. In this case, 103 stands for British or French date format, which is dd/mm/yyyy .

Declare @string char(10)='25/05/2016'
Declare @string2 char(5)='09:00'

SELECT CONVERT(datetime2, @string + ' ' + @string2, 103)

Result: 2016-05-25 09:00:00.0000000 ( datetime2 )

thanks marc_s for putting my query in the right format.

I tried this and got the expected result, please advise if there is any other optimal way, thanks

Declare @string varchar(20)='25/05/2016'
 Declare @string2 varchar(20)='09:00'
 Declare @string3 Varchar(20)=(SELECT Right(@string,4)+'-'+SUBSTRING(@string,4,2)+'-'+LEFT(@string,2)+' '+@string2)
 Select CONVERT(datetime,@string3) as _datetime

add this statement before convert

SET DATEFORMAT DMY

so query look like this

SET DATEFORMAT DMY

SELECT CONVERT(datetime, '25/05/2016 09:00')