Context I: ...Strategic Value?
Bonn has always had strategic value. A Roman fort was established in the area around 11 BC to guard the road between Cologne and Mainz. The 1^st Legion was stationed there. An allied tribe - the Ubii - were settled there by the Roman administration. When the settlement grew too large for the existing fort to be practicable, a newer, larger fortification was built nearby instead. This newer fortress - the largest of its kind to survive to the present day - remained in use until roughly the 5^th Century. As the Western Empire collapsed, much - if not all - of Bonn (then called Bonna) was destroyed by succeeding waves of marauding Germans.
Context II: ...Cultural Value?
Thanks largely to its strategic significance during the Roman era, Bonn became an important city in the medieval ecclesiastical administration; specifically, it was the seat of the Archbishopric of Cologne. For those Germans who spent their lives living in the vicinity of Cologne, then, Bonn held a special significance for its role as a medieval centre of temporal as well as spiritual governance.
Flash Forward: Early Post-War Germany
Konrad Adenauer, the first post-war Chancellor of West Germany, was born and raised in the vicinity of Bonn and had previously been a mayor of Cologne. Adenauer cherished Bonn and was personally responsible for moving West Germany's government there in 1949.
Bonn was a terrible choice for a capital city - it was small, culturally insignificant, and so lacking in government facilities that an entire complex of new government offices needed to be built. Bonn was so dull that it was often called the "Bundeshauptstadt ohne nennenswertes Nachtleben", or, "capital city without notable night life".
Frankfurt or Hamburg would have been much better choices: all the buildings required for such a government were already in place in those cities, and both places had the rich cultural heritages worthy of a national capital.
Bonn's dullness, however, was precisely why it was chosen: since German reunification was always West Germany's plan, and since Berlin was, and would remain, the 'true' capital of Germany, placing West Germany's temporary capital in Frankfurt or Hamburg would have seemed permanent, and would have made unification seem all the more improbable.
tl;dr: Bonn was chosen as the de facto capital of West Germany because it as a) dull as dirt and b) close to the home town of West Germany's first chancellor.
I assume you mean Bonn and just made a spelling mistake. Actually that is a pretty good question and I'm surprised that this has not asked before here -- at least not on my watch. The choice for Bonn as seat of government and in that provisional capital of the Federal Republic of Germany is something that's supposed to make people curious. After all, Bonn is a middle-sized city that -- while no doubt nice looking -- has no supraregional importance. Looking at West Germany, there are at least half a dozen cities that would supposedly make more sense as a capital, for historical, economic, or topographical reasons, all of them of larger size. Hamburg, Frankfurt a.M., Munich, Cologne come to mind immediately. So, why sleepy, picturesque Bonn?
There is a somewhat easy and straight answer to this question: Adenauer. Konrad Adenauer (you probably heard of him if you know a little recent German history) was the first chancellor of West Germany, ruling the young Federal Republic for 14 years (while simultaneously being foreign minister between 1951 and 1955), and the eponymous godfather of West German politics and the conservative party CDU. There was just no way around this guy in post-war Germany.
Konrad Adenauer was a born Rhinelander and Catholic, and allegedly didn't like the capital Berlin and "Prussian" East Germany anyway. He is credited with the strict alignment of West Germany with the Western powers regardless of popular opposition. After WWII Adenauer lived in the village Rhöndorf located closely to the southeast of Bonn. He was instrumental in bringing the CDU delegates in the constitutive Parlamentarischer Rat (the committee which wrote and agreed upon the provisional constitution for West Germany) to support Bonn in the council. The CDU's major rival, the Social Democrats (SPD), backed Frankfurt a.M. as capital, notably supported by a number of Hessian CDU members if I remember correctly.
Regardless of Adenauer's fondness of a short travel to work, there were indeed legitimate arguments for Bonn as provisional capital. As the city didn't have significant industrial potential it remained for the most part untouched by the Allied strategic bombing campaign and was not reduced to rubble as so many other German cities. Bonn's competitor Frankfurt a.M. for example looked like this after the war. Bonn had and has an impressive number of undamaged prestigious-looking buildings like the Villa Hammerschmidt or the Palais Schaumburg which proved to be of use for a newly set up government. Furthermore Bonn, located on the Rhine river, deeply seated into the valleys of westernmost Germany, was comfortably far away from the Soviet zone of occupation, which (at this time already foreseeable) was to become socialist East Germany. So it was a somewhat secure place too.
/Edit Just as a side note: Berlin officially never lost its status as capital of a unified Germany, which both German states claimed to represent (well, East Germany gave this up later and tried to establish the "two Germanies" status, but that's another story), but it was deemed as too risky by the West Germans to establish important ministries, insitutions etc. in a remote, isolated enclave like West Berlin, which in the case of all-out war would fall immediately into enemy hands. So, officially, Bonn became the seat of government while Berlin remained the symbolical capital.
*Bonn
