How do I do multiple assignment in MATLAB?

You don’t need deal at all (edit: for Matlab 7.0 or later) and, for your example, you don’t need mat2cell; you can use num2cell with no other arguments::

foo = [88, 12];
fooCell = num2cell(foo);
[x y]=fooCell{:}

x =

    88


y =

    12

If you want to use deal for some other reason, you can:

foo = [88, 12];
fooCell = num2cell(foo);
[x y]=deal(fooCell{:})

x =

    88


y =

    12