This is the shortest route to the summit of Ocejón (2.049 m) because the base is the highest, Collado de Soria (1.420 m). It is rare that you passes somebody on the trail but once near the top of Ocejón you'll join the people coming from the other more known routes.
The approach is by car or other motor vehicle from Campillejo (approximately 1.060 m) to Collado de Soria (1.420 m). There is a forest trail starting at that village either at the entry or at the end of it. The forest trail climbs for 6 Km, through a pinewood, to the SW ridge of Ocejón between Cabeza de Mostajar and Loma Lorente, to the col called Collado de Soria. After Campillejo leave a branch trail to the right and take the next one also to the right. Then the forest trail zig-zags on SW flank of Cabeza de Mostajar before reaching the col.
Leave your vehicle on Collado de Soria (1.420 m) and take the wide trail to the left (N). After 200 m leave the ruins of an ancient slaty shack to the left and pass through a young pinewood where the trail becomes a path. Be sure to remember the route at this point or build some cairns, it's so easy to leave the trail on the descent. Then start an endless ascent on the SW slope of Cabeza del Mostajar dodging the fields of rock roses that make the path difficult to follow. There is a slaty shack (not ruined) at 1.605 than could be used as bivouac for a person in case of storm. Go into a dirty fire-lane between an oakwood (left) and a pinewood (first, to the right), just at the beginning of the interminable slope. Once on the top of Cabeza del Mostajar (1.839 m - 1h 15 min) leave a rocky ridge to right first and then cross it to the right side (SE-E). Start to climb the final steep slope that leads to the summital comb. There is a 2 meter tall cairn until the true summit, wich is signed by a survey point (2.049 m). 2h 15 min.
The views over Sierra de Ayllón and Sierra de la Puebla are very beautiful from the top of Ocejón. The descent is on the same route. Pass Cabeza del Mostajar (1.839 m - 2h 45 min), try not to get lost in the young pinewood until reaching the ruins of the old slaty shack and reach Collado de Soria (1.420 m - 3h 45 m).
Crampons and ice axe are recommended in winter, wear warm clothes too. Do not forget map, compass and altimeter; they are very necessary in the fog or blizzard. Try to avoid the hotest days of the summer (15 July to 15 August) and wear a cap. Always take enough water with you because there is no drinking fountain or stream in the whole route.