We present results of photometric observations of the high-amplitude EC 14026-type star, Balloon 090100001. The data were obtained in broad-band B filter and span over five weeks, consisting of about 150 hours of observations. Fourier analysis of these data led us to the detection of at least 50 modes of pulsation, out of which 37 are independent. The frequencies of 22 detected modes are in the region of pulsations of EC14026-type stars, theoretically attributed to p-modes, and cluster into four narrow ranges, around 2.8, 3.8, 4.7 and 5.5 mHz, where the radial fundamental mode, the first, second and third overtones are likely to occur. Surprisingly, we also detect 15 independent modes in the low-frequency domain, between 0.1 and 0.8 mHz. These modes are typically found in PG 1716+426-type stars, recently discovered among cool B-type subdwarfs, and theoretically attributed to high-order g-modes. As both kinds of oscillations are observed in Balloon 090100001, it represents a link between the two classes of pulsating hot subdwarfs. At present, it is probably the most suitable target for testing evolutionary scenarios and internal constitution models of these objects by means of asteroseismology. Three of the modes we detect form an equidistant frequency triplet which can be explained by invoking rotational splitting of an ℓ=1 mode.