If you have just found that you are all out of capers or are not too keen on their briney taste then there are few items that you can substitute for capers available.
Some of these replacements may require a little bit of extra planing so it is best not to get caught out right when you need them.
What are Capers ?
Capers are the fruit(edible flower bud) of a plant called Capparis Spinosa(usually referred to a just the Spinosa plant). It is a small perennial bush like plant that has prickly thorns.
The Spinosa is predominantly found in Mediterranean areas. Depending on the area they range in size from that of a small pea up to roughly the size of an olive.
In most stores and supermarkets you will generally find the smaller variety in jars that have been pickled, in fact it is quite difficult to find them un-pickled.
What Do Capers Taste Like ?
Capers have a strong somewhat acrid taste. Which is in part due to the fact that they have been pickled.
Depending on where they have been prepared they can either be pickled by soaking for long periods in either vinegar or a traditional salt brine.
For many people capers taste like they have been pickled a little bit too much and this is the common complaint among those who dislike them.
Substitute for Capers
A lot of people do find the taste of capers a little to sharp for their liking so if you are having friends around and a recipe calls for them then it's good to have a few alternatives available.
Capers have a fairly distinctive taste so there are a limited number of substitutes available.
Green Olives

Green olives are a great way to replace capers especially if you do not like strong or sharp tastes.
Be sure to find olives that have not been stuffed with pimento as this will change the flavor profile of the olives significantly.
Better yet is to purchase fresh ones that still have the stones in. Green olives when bought like this retain most of there natural flavor.
If you can combine the freshly pitted olives with a little salt, vinegar and oil you can come as about as close to the taste of capers as possible.
Be sure to vary the amount of salt and vinegar over several small batches to find the correct ratio that suits you best.
Black Olives
Like the green olive above if you are going to use black olives as a substitute for capers then try to purchase fresh ones from a deli.
Black olives that come in a jar tend to lose a lot more flavor than the greener variety. In fact most black olives that come in a jar have a very flat taste to them when compared to freshly bought ones.
Thyme

Thyme is probably the best herb to use as an alternative to capers in a recipe. It has a fairly similar flavor and adds an aromatic smell to almost any savory dish.
If you are using a large amount and do not want the stems to end up in the final dish the the best option is to tie the stems together as in the picture above.
You have the option of using either fresh time on the stem or dried/ground thyme that is available in most stores.
Nasturtium Seeds
Nasturtium seeds or flowers can be eaten whole and have a peppery like taste.
You can make your own replacement by obtaining the seeds and soaking them along with a few pepper corns and some garlic in a small vinegar solution.
The one major drawback with Nasturtium is that it can be very difficult to obtain.
If you are thinking of popping out to the shops to get some then you may end up visiting quite a few places and depending on where you live you may not find any.
So as you can see the potential list of ingredients to use as a capers substitute is not all that great.
However, with a little bit of upfront planning the ones listed above are easily your best bet to try and recreate it's rather distinctive taste.