Hi,
In the HikaShop backend, you will find an "invoice" button in the toolbar when you see the details of an order.
That invoice will be in HTML, can be printed and can be customized (view order / invoice).
Now it is also possible to generate PDF invoices, thanks to that plugin :
www.hikashop.com/component/hikashop/product/cid-18.html
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.