IF USING YOUR HANDS:
may i suggest creating one column with date+time,
if will be easy to increment (write two first lines, select them, then
right clic the small square in the right-bottom, go down, stop on the
final date, in the menu choose to increment as a serial list; not
integer one !)

then put in two adjacent colmuns the formulas:
(example : my column in A, date in B, time in C)
in B1: =DATE(YEAR(A29);MONTH(A29);DAY(A29))
in B2: =TIME(A1)

for each one right-double-clic the right-bottom-square
the formula will propagate down to the end of list

select thoose 2 columns copy / paste-special the values
delete the column A

you have your result

IF USING A MACRO:
then you may add a constant value one to the other
(the step constant must be:
[ {(sec)/60 + min}/60 + hour ]/24 + day
)

and that's all

well, excel knows how to work with dates
you do not need all thoose tests (if sec 60 ...)

=================
Sub test()
Dim i&, D As Date, TimeStep As Date, Cell As Range

Set Cell = [A1] ' first cell to write
D = "8-7-2005 00:00" ' start date
TimeStep = "03:05:00" 'date/time increment

For i = 0 To 9 ' 9 means 10 cells
Cell.Offset(i, 0).Value = D
D = D + TimeStep
Next i

End Sub
===================


then , you'll need to understand that excel will change the cell's
format when writing in an empty cell a new data. For example, if you put
a date, the date format will be selected. But if you are entering a
date+time date then the date+time format will be selected.

But if you write a date in an old cell with an other format, then the
date will not be written as wished. You may change the format of cells
before writing into them...

doh - just thought - of course the dates are manipulated first and then
added to the string.
BTW I managed to finish my project using my old methods but this is useful
info.

well take a better look: these are not strings

they are converted from strings to dates
just because of the Dim declaration

D is supposed to be a date, so D = "..."
makes VBA try to convert the "..." to the date type.

But you may use D = CDate("...") if you want to much more understand the
key of my code. (this CDAte is auto-added by VBA by default)

well take a better look: these are not strings

they are converted from strings to dates
just because of the Dim declaration

D is supposed to be a date, so D = "..."
makes VBA try to convert the "..." to the date type.

But you may use D = CDate("...") if you want to much more understand the
key of my code. (this CDAte is auto-added by VBA by default)

Many thanks,

I have improved my code by using your method - it saved me a lot of time and
stress.

Cheers

JS