By accessing this property, you can read or change the contents of any cell. 

To read or change the cell format, use CellFormat property. 

To read or change both the cell format and the value, together, use Cell property. 

If you have a string with a value and want to enter it in Excel on the best possible way (if it is a date, as a date, if it is a number as a number, etc) take a look to SetCellString 

If you want a formatted string instead of it's raw value, take a look at XlsFormatValue 

TFlexCelImport Properties